Before I start talking about everything else, let me tell you a little about myself. I have been working at Tire Rack since 2005.
I first visited the South Bend headquarters in 2003 as a customer looking to buy a set BMW wheels and tires. I was impressed with the showroom and test track, and I thought it would be fun to work here. That idea stayed with me, and within a couple years I joined the team.
Like most of us here, I am a car enthusiast. I really enjoy the tire testing we do here, especially the track tests, and it is fun to talk to enthusiasts from all over the country and around the world.
Before I start talking about everything else, let me tell you a little about myself. I have been working at Tire Rack since 2005.
This spring, BFGoodrich is introducing the new g-Force Rival S. Building on the successful design of the original g-Force Rival, BFGoodrich is expanding the line to include the S version. The primary difference is a softer compound that will come up to operating temperature faster and yield higher maximum grip. This is ideal for autocross competitors, time attack participants or anyone who needs maximum grip for short periods of time.
The g-Force Rival S does not replace the original g-Force Rival, which remains a better choice for cars that run longer track sessions like driving schools, lapping days and budget endurance races like 24 Hours of LeMons and Chump Car. The Rival S claims enhanced wet traction, but the biggest emphasis is on dry traction, and neither tire is recommended if serious wet traction is required. The Rival tread pattern is not ideally suited for wet weather performance, though they can certainly be driven in the rain if the driver exercises due caution.
g-Force Rival S tires retain a 200 treadwear number, which will keep it legal for most street-tire racing classes. It will be legal for SCCA Solo national events once the required six sizes covering four wheel diameters are available.
We look forward to putting the BFGoodrich g-Force Rival S through its paces once the weather warms up here in South Bend!
It's notoriously difficult to find tires for the original Jeep Grand Cherokee SRT8. Staggered sizing and short sidewalls means very few choices, and none of those choices are intended for serious off-road use. And while most SRT8 owners don't plan to venture off the road, a Jeep is still a Jeep! There is always some temptation to head for adventure off the beaten path.
The newer Grand Cherokee SRT8, running 295/45R20 on all four corners, isn't much better for finding off-road tire options. However, the vehicle will fit the slightly larger 305/45R20 size. While it isn't a common size, it does provide Cherokee SRT8 owners the option to install the Yokohama Geolandar A/T-S.
Consistently ranked in the top ten in survey results in the On-/Off-Road All-Terrain performance category, the Geolandar A/T-S provides a nice mix of solid road handling with traction capability on loose surfaces. It's also designed to deliver long mileage and promote even wear while providing year-round traction, even in the snow.
If you want to let your SRT8 show its Jeep side, then take a look at the Yokohama Geolandar A/T-S.
The Extreme Performance Summer tire category has become increasingly competitive in recent years. Bridgestone's Potenza RE-11 has been one of the most popular and well-reviewed tires, but they can't afford to rest on their laurels. The Potenza RE-11A provided a refresh in select sizes to enhance their competitiveness against their newest rivals. And while the RE-11A is currently at the top of the class for customer survey ratings, Bridgestone is already preparing to release an all-new design.
The RE-71R features a design with all-new compound, construction and tread design. How will it stack up against the competition? We're not sure yet, as Bridgestone has not started delivery. It also doesn't help that our test track is currently buried in snow! But rest assured, we'll be testing them as soon as we can. Slinging BMWs around a racetrack on ultra-sticky tires? Well, it's a tough job, but someone's gotta do it!
Stay tuned for future updates on this new, exciting tire from Bridgestone.
I had a question from a customer that surprised me the other day. After doing this for as many years as I have, I tend to think that I've heard it all. We were talking about an older BMW, and he asked me if the original tire sizes were staggered. I replied that they were not. His follow-up question was, "Well, why not? It's not like the car is all-wheel drive."
There are a couple of assumptions in that simple question, and they are a mixture of true, false and revealing statements.
Assumption #1: All-wheel drive cars do not or can't have staggered tires.
Assumption #2: If a car can have staggered tires, it should or is expected to.
Assumption #1 is somewhat accurate, but isn't set in stone. Many AWD systems will wear prematurely if there is too much difference in the rolling diameter of the tires. And, it's hard to get staggered tires with perfectly identical diameters. They are usually close enough that it looks identical, but the actual revolutions per mile may be too different than a given AWD system can tolerate.
With that said, there are some vehicles that come with staggered tires from the factory. And in fact, the first example off the top of my head comes from within the BMW marque that we were discussing. The X5 is AWD (or xDrive in BMW-speak) and many of them have staggered 20" or 21" sizes.
Assumption #2 is the one that really surprised me. Staggered wheels and tires have become more common in recent years, and it seems they've become ubiquitous enough that some people think of that as the default configuration. This still blows my mind!
The default configuration for a car or truck is to have all four tires the same size. This set-up has a number of advantages. First, It is easier to find tires when one does not have to look for something that is available in two different sizes. The tires can be rotated from front to rear to help maintain even treadwear.
Next, there is less chance for confusion. I've seen staggered set-ups installed with the back on the front and vice versa; and I've seen customers assume that if they check the size of one tire, that all four tires will be that size. Also, a full-size spare or extra tire can be used on any position of the vehicle.
With that said, there are a few reasons to go with staggered tires. One is weight bias. If you have a car that has a large majority of its weight over one axle, that axle should have bigger tires. See Porsche 911s with their rear-engine weight bias as an example.
Two is power. If you have a rear-wheel drive car that has a lot of horsepower, you may need bigger tires on the rear to help put that power to the pavement. Why not just make all of the tires bigger in that case? The size of the front tires is often limited by the fact that the front wheels have to steer left and right. Too wide of a tire may rub when the steering wheel is turned. Super-wide tires in front can also aggravate the tendency to hydroplane when hitting puddles, and may make the steering feel unduly heavy.
Three, and often the most relevant, is style. The staggered look, with big tires on the back, is generally considered to be cool. I think part of that is driven by the fact that it's usually the more exotic cars that need staggered tires: rear or mid engine, high horsepower, RWD. These attributes describe some of the most iconic cars in history, from the Ferrari F40 to a Top Fuel dragster. Such is the cachet of wide rear tires, that I will often have customers with FWD cars ask for a RWD-style staggered set-up, causing Isaac Newton to spin in his grave at 8,500 RPM. (For the right way to stagger FWD, take a look at "Automotive Oddity: Correctly Staggered Tires on a Front-Wheel Drive Car")
In the case of the old BMW, it had balanced weight distribution and horsepower, that by today's standards is moderate, and the staggered-tire style trend was not nearly as widespread in the late 1980s. Therefore, there was no reason for it to diverge from the normal tire configuration. I didn't bend my customer's ear with all of these musings, but a highly condensed version was enough to give him the general idea.
Our Recommended Installer's page is designed to help make installing the tires you get from us simple and convenient. To learn about choosing an installer, take a look at "Updates to Our Recommended Installer Page Help You Find Your Ideal Installer."
All of our Recommended Installers take part in our Price Pledge program, meaning that they promise to accurately display their installation costs on our site and stick to them. Not all installers have the same prices, but they all must adhere to the prices they publish.
Enter your ZIP code to see the list of installers in your area. All of the pricing for mounting and balancing is based on the tire's aspect ratio, which is the middle number of the tire size. If your tire size is 205/55R16, your aspect ratio is 55. Therefore, you would look at the pricing line for "50-55 Series" tires. If you are not sure of your tire size, it will be indicated on the side of your tires.
Here is an example of an installer pricing guide. This is for installation at our South Bend headquarters. Note that the basic installation/balance pricing is on the left hand side.
The right hand column of an installer listing is for "Additional Services." Not all of these will necessarily apply. Valve stems are normally replaced when changing tires. Some cars may have valve mounted tire pressure monitoring sensors (TPMS). In that case, disregard the valve stem charge. You may need to have the sensors serviced, in which case you would include the pricing for TPMS service instead.
Tires for larger trucks may be subject to additional cost, and the same goes for run-flat tires. Be sure to factor these charges into the cost if applicable.
Many shops will have a disposal fee to handle proper recycling of your old tires. This does not apply if you are keeping your old tires or disposing of them yourself. Some shops will have a shop fee to cover miscellaneous materials and shop overhead.
When reading the tables, you will often encounter N/C or N/A. N/C means that the service is included at no cost with the regular installation price. N/A means that the service is not offered by that installer. For example, if the line for Run-Flat Tire Service reads N/C, that means the shop installs run-flat tires for the same price as regular tires. If it says N/A, that means the installer does not handle run-flat tire installation.
If you need additional services not listed on the basic pricing table, click on the installer that you are interested in. You will see an expanded view with more services listed, as well as the contact information for the installer. If the service you want is not priced on the expanded table, you can check with the installer directly.
While there are many items to consider, our Recommended Installer page puts everything right in front of you so you can easily compare costs among the different installation options.
Eibach springs are one of our most popular suspension products. For most applications, Eibach offers both Pro-Kit and Sportline springs. Which one is best? The answer, as always, depends on what you are looking for.
The Pro-Kit is an excellent blend of ride and handling. Moderate lowering, usually an inch to an inch and a half, gives a sportier appearance but does not look radically customized. Since the lowering is not extreme, special alignment kits are generally not required. The ride is firmer than stock, but still comfortable. The feel is generally similar to the sportier end of what factory sport packages are like. For an enthusiast looking to enhance the fun-factor of their daily driver, this options is usually just right.
The Sportline gives more substantial lowering, usually more than an inch and a half, and often two inches or more. A more aggressive drop means that the springs need to be stiffer. While still meant for street driving, they're suited to a more hardcore enthusiast. The additional lowering may require special alignment parts, particularly a camber kit, in order to maintain proper alignment specs.
Shop by vehicle to view the suspension products available for your application.
As a high-horsepower RWD car that comes with summer tires, the M3 desperately needs winter tires if you are going to drive it through wintry weather. Both the E90 and F80 M3 commonly come with 19" staggered wheels, which makes snow tires hard to find.
In previous years, the Bridgestone Blizzak LM-60 was available in 255/35R19 front and 275/35R19 rear, but these have been discontinued and the replacement does not come in both sizes.
This year, the best winter option is the Pirelli Winter Sottozero Serie II, which is in stock in both sizes. With highly effective brickwork sipes, the Sottozero offers a multitude of biting edges to generate snow traction for accelerating, braking and cornering. With a W-speed rating, the Pirelli tire exceeds the performance potential of most other winter tires. Even performance winter tires usually max out at a V-speed rating.
While the M3's low ground clearance and wide tires will limit its effectiveness in deep snow, an M3 (or M4) outfitted with a set of winter tires can be a surprisingly capable vehicle in moderate snow.
To prepare your M3 for the winter, take a look at the current pricing and availability of the Pirelli Winter Sottozero Serie II.
The Blizzak WS70 was Bridgestone's flagship ice and snow tire through last winter. The introduction of the Blizzak WS80 for this winter has led to the discontinuation of the WS70. However, there are still some popular sizes of this tire in stock and available at closeout prices.
Though it doesn't quite equal the performance of the newer WS80, the WS70 is still one of the best winter tires available. As one of our customers from Michigan recently said about the tire when a November snowstorm arrived, "A week after I installed the tires, we received over 24 inches of snow. The tires performed much better in snow and slush and on ice than the Original Equipment all-seasons that came with the car. I did not get stuck once and they plowed through over seven inches of snow without slipping."
With winter already here for many, now is a great time to take advantage of closeout pricing on this strong-performing winter tire. For example, 195/65R15 is one of the most popular passenger car tire sizes and is currently available for $75 per tire. The tire is not only priced lower than many other options, it outperforms a number of them in ice and snow traction.
View all remaining sizes and see if one is a fit for your application.
The 2014 Honda Accord is one of the top-selling cars in America. In most cases, it comes equipped with Michelin or Goodyear all-season tires, which are suitable for mild winters. If you reside in an area that experiences severe winters, with substantial snowfall and icy conditions, a set of winter / snow tires will be a big improvement over your Original Equipment.
Our Preferred Package for this vehicle uses the Bridgestone Blizzak WS80 for outstanding ice and snow traction. We mount them on value-priced black steel wheels.
One reason to purchase them installed on wheels is convenience. With the tires already mounted and balanced, you can change them yourself with just a jack and a lug wrench. Try getting an appointment at the local tire store when the first snow of the winter is about to hit and you'll quickly appreciate the flexibility of a do-it-yourself installation. To read about my personal experience of installing my own Tire & Wheel Package, check out "Why I Love Having My Winter Tires on Wheels."
Another great reason is preservation of your summer wheels. Winter roads are coated in slush, salt and other melting agents. These conditions can quickly leave your wheels looking sad and dingy. Let your winter wheels take the abuse, then put your nice, shiny wheels back on in the spring.
Also, the cost of mounting and balancing makes getting winter wheels a no-brainer. With an average mount and balance cost of $15 or more per tire, each time, that's a cost of $30 per tire, per year. With a wheel that costs approximately $60, it pays for itself in two years.
Start shopping and find a Winter / Snow Tire & Wheel Package for your vehicle.
Our annual test on a local indoor hockey rink gives us an early look at how this year's winter tires will perform on one of the most challenging driving surfaces there is: a sheet of ice. This year, as we commonly do, we focused on the Studless Ice & Snow performance category. This class of tires includes the most innovative winter compound technology and is very competitive. Tires in this class also are designed to maximize snow and ice traction.
Studless Ice & Snow tires meet the challenging winter driving conditions by delivering studded-like snow and ice traction without employing noisy, road-damaging studs. These tires feature pliable tread compounds molded into purposeful tread designs that trade some handling in dry and wet conditions to deliver outstanding snow and ice traction. Tires from this performance category typically are for drivers of coupes, sedans, minivans and crossovers.
It's quite impressive to experience the level of grip that these tires can generate even on a smooth sheet of ice. While the traction control and ABS certainly help, they can only work within the limits of grip supplied by the tires.
During our test, we compared the new Bridgestone Blizzak WS80, Dunlop Winter Maxx, Michelin X-Ice Xi3 and Yokohama iceGUARD iG52c. All four tires performed well. The Bridgestone Blizzak WS80 and Michelin X-Ice Xi3 provided the best traction overall. The other two tires were slightly behind the Bridgestone and Michelin tires.
For a complete recap of our test, take a look at "Studless Ice & Snow Winter Tires: Finding Which is Best When Winter Weather is at its Worst."
Tough enough to drop from an airplane! To demonstrate the enhanced toughness of their new All-Terrain T/A KO2, BFGoodrich mounted them on wheels and dropped them from the sky.
With the majority of all-terrain tires' punctures happening in the sidewall area, BFGoodrich paid special attention to reinforcing the sidewalls with technology from their off-road racing Baja T/A KR2. Some sizes of the All-Terrain T/A KO2 are already in stock. More sizes will begin to arrive in the coming weeks and months. The goal is to make the tire available in all popular sizes in the all-terrain market.
This second-generation KO tire is developed to meet the needs of jeep, pickup truck and sport utility drivers who want confidence and control on- and off-road. It's designed to deliver go-anywhere traction along with outstanding durability, great wear and year-round traction, even in snow.
Of the 12 tires that BFGoodrich dropped in the course of making this video, only one of them deflated. The reason: the wheel itself cracked. The tire was not harmed!
With winter fast approaching, you may be wondering whether to stick with your all-season tires or go to dedicated winter / snow tires. If you have never experienced the difference, winter tires make a very noticeable difference in every aspect of winter driving.
Acceleration, braking and cornering ability are all significantly improved when using winter tires. How much are they improved? In our test, "All-Season vs. Winter (Passenger Vehicle): The Difference Between Wintertime Gripping and White Knuckle Snow Slipping", we compared an all-season's capabilities to those of a winter tire on our test track.
We learned that while all-season tires may provide enough traction in winter in parts of the country that receive light snow, there isn't a viable alternative to dedicated winter tires. If you encounter heavy snow, frequent slush and icy conditions, shop by vehicle to find a set of winter tires for your application.
Tires are often the difference between wintertime gripping and white knuckling slipping, and only a set of four winter tires will do! Since it's imperative to keep the same level of traction at all four corners, installing winter tires in a set of four allows you to maintain the most balance and control as possible. To learn more about installing a set of winter tires on your car, read "Four Winter Tires...The Only Way To Go."
If you need excellent ice and snow traction on a budget, take a look at Yokohama's iceGUARD iG52c. This tire is new to our lineup this year and provides a very attractive price-point in the popular Studless Ice & Snow performance category.
Taking the popular 205/55R16 size for example, the class-leading Bridgestone Blizzak WS80 is $126. Compare this to the Yokohama option at $102 per tire and this saves almost $100 on a set. While this tire may not provide the same level of performance as a Blizzak tire, it does well compared to driving in winter conditions on all-season tires. Featuring advanced winter tire technology, the tire is proficient in cold temperatures on dry, wet, slushy and snow-covered roads.
iceGUARD iG52c tires feature Yokohama's BluEarth branding to identify an ecologically friendly series of tires that are designed to deliver environmentally, human and socially friendly solutions. The IG52c is available in a wide range of sizes, and performed very creditably in our ice rink testing this season. If you want the confidence of a true ice and snow tire at an affordable price, they are hard to beat.
Take a look at all Yokohama winter tires available and see if one's a match for your application.
Sport Edition A7 wheels are available in both black and silver. It's still the go-to wheel for a practical winter package. They are a direct fit with no spacer. They will even use the original bolts and can accept a BMW cap. I like this wheel so much, that I used it for three winters on my previous BMW.
Though the Sport Edition A7 is the most common 18" winter wheel, there are a few alternatives that we have available. BBS' CH can work, though there aren't many available at this time. They have also introduced the XA this year. While we do not have them available in our distribution centers at this time, we can order them for you to have in time for the winter season.
There's good news for those drivers who are in need of serious snow traction - Bridgestone has introduced the Blizzak WS80. The Blizzak WS80 is an upgrade to to their WS70. They are available in the 235/40R18 and 245/40R18 sizes that are suitable for square set-ups on 18" wheels. This tire is H-speed rated and not oriented toward sporty handling. It's truly designed for maximum snow and ice traction.
When it comes to staggered set-ups, there's always a challenge in selecting snow tires. If you have staggered 18" tires, nothing matches perfectly in the stock 245/40R18 and 265/40R18 sizes. There is a Pirelli Winter Sottozero Serie II that is a Porsche spec rear and Mercedes Original Equipment in the front you can consider as an option. Also, in the 235/40R18 and 255/40R18 size, there are several matching options to consider from Bridgestone, Dunlop and Michelin.
For those drivers considering 19" wheels, the Pirelli Winter Sottozero Serie II comes in the stock sizes. The 255/35R19 and 275/35R19 Blizzak LM-60 that had been popular with drivers has been replaced by the Blizzak LM-32. The front tires are H-speed rated, while the rears are V-speed rated. Mixing speed ratings is not ideal, but it's better than driving in harsh winter conditions without snow tires.
Create your Winter / Snow Tire & Wheel Package today!
The easy answer to this question is: winter tires! All specialized snow tires have traction on ice and snow that exceeds the best all-season tires.
How do you know which winter tire to choose? Typically, the Bridgestone Blizzaks have been class leaders in ice and snow traction. Since their introduction in 1993, we haven't found an all-season tire that can match the Blizzak's confidence-inspiring combination of deep snow, packed snow and ice traction.
Blizzak tires feature dual tread compounds consisting of outer tread cap and underlying base compounds. These tires wick away the thin layer of water that often develops on the top of packed snow and icy roads, allowing biting edges to better adhere to the surface for more traction.
However, competitors are offering even tougher competitors to the Blizzak line. For example, Michelin's X-Ice Xi3 gave a strong challenge to the Blizzak WS70 last year. It offers a good blend of traction and road manners. It also meets Michelin's Green X standard for low rolling resistance by reducing vehicle fuel consumption and emissions from CO2 gases.
When considering winter tire options this year, be sure to take a look at the new Blizzak WS80. We had a chance to take part in an introductory test pitting it against its rival from Michelin. For a complete recap of the test, read "Bridgestone Blizzak WS80 Introductory Test Report."
When purchasing winter tires, also be sure to consider a dedicated set of wheels.
Many customers call in asking what's the difference between the Pirelli Cinturato P7 All Season and Cinturato P7 All Season Plus. The tread pattern is the same. They are both all-season tires. They are usually offered in the same speed ratings. So, what makes the "Plus" a distinct model?
Pirelli Cinturato P7 All Season
Pirelli Cinturato P7 All Season Plus
The key difference is in the compound - compared to the Cinturato P7 All Season, the Cinturato P7 All Season Plus has longer treadlife. It is also developed to be environmentally friendly with Pirelli's EcoImpact icons confirming the tire's contribution to the environment with regards to energy efficiency, clean air, low noise and long wear. Cinturato P7 All Season Plus tires offer lower weight, less rolling resistance and reduced noise while enhancing wet braking and year-round traction, even in light snow.
Environmental friendliness, safety and performance are essential features designed into many Pirelli tires. Their innovative compounds, internal structures and tread patterns are designed to lower vehicle fuel consumption and carbon dioxide emissions, while providing longer tire wear without compromising performance. Pirelli's green performance strategy has developed new production systems that reduce environmental impact and energy consumption while focusing on quality and safety. This has resulted in lowering factory water consumption levels, energy use and emissions.
For more information on Pirelli's green performance strategy, read "Pirelli EcoImpact."
Summer testing is in full swing at Tire Rack, and the first test report for the new Continental TrueContact have been published. This new Standard Touring All-Season tire hit all the right notes with a smooth, quiet ride and solid wet and dry traction.
During our test, we put the tire up against the Firestone Precision Touring, Goodyear Assurance TripleTred All-Season and Michelin Defender. In the abrupt maneuvers portion of the test on our track in dry conditions, all four options performed well and with nearly identical results in stopping distance, cornering traction and average lap time.
We liked the TrueContact's tight handling, to go along with its slight edge in observed fuel economy. With its well-rounded character, the TrueContact took top honors in a very competitive test group. A couple of highlights from our testers include:
"The ride of the Continental TrueContact can be best described as taut and well controlled without being harsh."
"Wet weather traction is a bigger separator than dry. And in this test group, the TrueContact showed a noticeable advantage in overall traction and stability during the wet handling test."
For a complete recap of our test, check out "Testing Passenger and Standard Touring All-Season Tires: Which Are Truly More Than Just Round and Black?"
Many drivers are uncertain whether they can put non-run-flat tires on wheels that originally came with run-flat tires. The short answer: yes.
Run-flat tires and regular tires that are the same numeric size will have the same physical dimensions, and can fit properly on the same wheels. The only difference with run-flat wheels is they usually have an extra hump behind the bead seat. This hump would help keep the run-flat tire in its proper place on the wheel while driving without air pressure. It does not affect the performance or compatibility of the non-run-flat tire.
A few words of caution: If you are changing to non-run-flat tires from run-flat tires, make sure you have a plan for what you will do in the event that you do have a flat tire. An air compressor and sealant can easily seal a minor puncture. A plug kit can also be useful for a temporary repair. You should have some sort of roadside assistance that you can call if you have a larger puncture. Some cars may have space to store a spare tire, though some cars with run-flats do not have any convenient location for the tire.
If a spare tire is an option, remember that you should maneuver more cautiously when your vehicle is equipped with a Temporary/Compact Spare tire and three standard tires. Any differences in tire traction can reduce vehicle handling and increase braking distances, especially in emergency situations.
Whether you're looking for a set of non-run-flat or run-flat tires, shop by vehicle and view all options available for your application.
We're glad to announce the opening of our newest distribution center in Denver, Colorado. After months of preparation, our staff is ready to take orders which will improve delivery times and inventory availability for the western part of the country.
If you reside in the Denver area, you're welcome to place an order for pick-up. Take a look at the contact information page to view a map to help you locate the distribution center for picking up your order.
Additional Denver distribution center information:
- Address: 9690 East 40th Avenue, Denver, CO 80238
- Phone: Please contact our headquarters for assistance with your order at (800)-428-8355.
- Hours: 8:00 a.m. to 5:00 p.m. (MST) Monday through Friday
- Installation is not available at this location. Orders are for pick-up only.
For more information on the Denver distribution center, view here.
A punctured tire is never a joyous occasion, but if it can be repaired, the hassle and expense are often minimal. Some factors are beyond a driver's control, however there are steps that you can take to maximize the chances that a flat can be repaired.
Aside from blowouts and large gashes in the tire that are obviously not repairable, there are three main factors that determine if a tire can be fixed:
- The size of the puncture.
- The location of the puncture.
- Whether the tire was driven on while flat.
With regard to size, if the puncture is 1/4" diameter or smaller, it may be repairable. If the hole is larger than 1/4", replacement is required.
As far as location is concerned, punctures in the tread area of the tire are often repairable. Punctures in the sidewall or shoulder of the tire are not. While it may be physically possible to plug the hole, the flexing of the sidewall is likely to work the repair loose.
Driving on the flat tire is the biggest item under the driver's control. Driving even a short distance on a tire that has lost pressure can leave it unfit for future service, even if the actual puncture is perfectly repairable. Damage to the sidewall from running without air pressure makes the tire unsafe for future use. For detailed information on repairable and non-repairable punctures, read "Flat Tire Repairs - Past the Point of No Return."
If you hope to save the tire, stop immediately when you have a flat as long as it's safe to do so. If the tire looks like it can be repaired, change to the spare, make a temporary repair to re-inflate the tire or have the car towed to a service location. Then make sure to have the tire properly repaired with both a patch and plug.