Goodyear Marathon Radial vs. Power King Towmax STR Trailer Tires

The nice weather is here and many trailers are hitting the road with spring projects. Are your trailer tires in need of replacing? Until recently, Tire Rack only carried the Goodyear Marathon Radial trailer tire. For information on this Trailer Service tire, read my previous blog post, "Trailer Tires are Available at Tire Rack."

We now offer a few more tires in this performance category, including our newest option, the Power King Towmax STR. Like the Goodyear Marathon Radial, the Towmax STR tire is designed for use on campers, boat trailers, fifth wheel trailers and even some larger utility trailers. The tires also share some common design features, such as a symmetric tread pattern and twin steel belts with reinforced nylon caps to help increase overall durability. 

Unlike the Marathon Radial, the Towmax STR is produced in the popular 235/85R16 load range E size that many full-size trailers use. Another unique application is the 225/75R15 size that's available in an E load range versus only a D load range with the Goodyear Marathon Radial. 


Listed below are the available sizes for the Power King Towmax STR trailer tire:

Trailers will be more stable and pull better on tires designed specifically for trailer use. Special Trailer tires are constructed with heavier duty materials and are tougher than typical passenger vehicle tires. To gain a better understanding of the driving requirements of Special Trailer tires, read "Trailer Tires vs. Passenger Vehicle Tires."


Thursday, October 18, 2012 by Trevor

Are the Power King Towmax STR Trailer tires a Radial tire?
Thursday, October 18, 2012 by Gary


Yes, all of the Power King Towmax STR Trailer tires are radial tires.
Friday, October 26, 2012 by Ken Foust

I have a brand new power king spare. I bought my unit in 2007. Is the trie still good to go??
Friday, October 26, 2012 by Gary


I would feel okay using that spare given that has been protected from sunlight and the elements for most (if not all) of its life.
Wednesday, February 20, 2013 by JIM

What country are the Power King tires made in ?
Wednesday, February 27, 2013 by Jim

I have a new trailer with two axl;es and 215 75 R 14 tires.
I would like to upgrade to an E load rating. There isn't much extra room in the wheel wells for a 15" tire.
Can I get a 14" E rated tire? If not why not? Many trailers use the 215 14" tire and they are almost overloaded empty. This needs to be rectified.
Wednesday, February 27, 2013 by Gary


I'm sorry, I have not heard of any E load range 14" tires, sorry.
Wednesday, May 22, 2013 by Brian

We have a 5th wheel trailer that weighs 12k lbs loaded, with about 2,000 of that on the pin. So, 10,000 lbs sitting on 4 tires. The OE tires were 285-50-20 on American Dominator wheels. The first owner replaced these with 275-65-20 Load Range E tires. The problem is that the wheel wells are not large enough to accomodate the tall profile and they rub. I am looking for Load Range E tires in the original 285-50-20 size but cannot find any,only XL Extra Load. Is XL a high enough load rating for the trailer? Some people with this model trailer have "downgraded" to the base 16" trailer tire in a Load Range E. I am tempted. Am I ok with a set of 285-50-20 XL's? or are there reasons the 16" combos would be better?
Thursday, May 23, 2013 by Gary


I do not show any more XL tires available in 285/50R20. Most other tires in this size carry less than 2500lbs per tire so I could not recommend them. There are still many load range E tires made in 16" sizing, so you may want to consider going that route, or modifying your fenders to help with the rubbing on your current size.
Tuesday, June 4, 2013 by Stan

what is the speed rating of the ST205/75R15D ?
Tuesday, June 4, 2013 by Gary


Industry standards dictate tires with the ST designation are speed rated to 65 MPH.
Monday, July 15, 2013 by Keith

What country are the Power King tires made in ?
Monday, July 15, 2013 by Gary


Like the Goodyear Marathon Radial Trailer tires, the Power King TowMax STR tires are also made in China.

Tuesday, August 13, 2013 by Mary

Looking to replace my current horse trailer Power King tires but not sure if they are D or E rated.
Tuesday, August 13, 2013 by Gary


What is the maximum inflation pressure listed on the tire sidewall?
Monday, September 9, 2013 by joe

I currently am looking for new trailer tires for a 10,000lbs trailer, it mainly pulls a 7,000lbs tractor. The tires currently use a st225/75r15 D rating, I would like to up grade to load E. My question is will the increase in max pressure while inflation cause structural problems to the rims? or it ok because it is jumping from an inflation of 65psi to 80psi
Monday, September 9, 2013 by Gary


Increasing the inflation pressure to 80psi with a load range E tire should not cause any structural problems for the wheels.
Friday, November 8, 2013 by Nancy

I currently have Good Year Marathon 225 75 15 D, ST tires on my horse trailer. I would like to go to a E, is that Ok. Also which is a better tire the Marathon or Maxxis?
Monday, November 11, 2013 by Gary


Goodyear does not make the Marathon in a load range E in 225/75R15, but the Power King Towmax STR tires are made in that size in an E load range.

Monday, May 19, 2014 by Chuck

Wanting to go from a 15" to a 16" on my rv.Im getting bad mpg on the 15s thinking going to 16" as the 15" are getting 733 rev. per mile but my truck tires are getting 654 rev per mile.Im thinkin the trailer is fighting to keep up.What do you think will the 16" E rated tires make a big difference in mpg over the 15" D rated tire?
Tuesday, May 20, 2014 by Gary


I'm sorry, we have no data on the effects of this change on MPG
Friday, May 23, 2014 by Resa

I have a 25 ft rv with tire size St225/75R15 but I do not see a load size and have no idea what the trailer weighs. How do I know if I need a D or E load tire? Currently it has Goodyear but woould the Power King Towmax be a good tire for this RV. I pull it with a dual wheel crew cab. I live in this unit also.
Wednesday, May 28, 2014 by John

I have a fifth wheel toy hauler with power king tow max str tires that are two years old. I have had three blow outs in three months on two different trips. GVWR/PNBV is 16,500 the trailer empty is 12,180. Tires came with the trailer-2012. I normally tow at 15,000. Are these the wrong tires, why do they keep blowing.
Wednesday, May 28, 2014 by Gary


What is the maximum inflation pressure that is listed on the sidewall of your current tires?
Sunday, July 20, 2014 by Chuck

This is my first set of Power King Towmax STR ST235/80R16, that came on my 20013 5 th wheel, less then 1000 miles on them they are junk! tread coming apart, needles to say I will be putting a new set of Goodyear Marathon Radial back on my rv, never had any issues with them ever!
Thursday, July 24, 2014 by Alex

I have been reading about the ST tires, and the speed rating on the STs are quite a bit lower than speed rating on an LT tire. I pull a horse trailer with 235/85/16. I generally don't go much over 65mph, but I do on occasion. How important is the speed rating on a tire? I have been using LT tires on it for years, and I do want the best tire for it, but I don't want a tire that can't handle some speed when I need it. Thank you.
Friday, July 25, 2014 by Bob

You stated that trailer tires ST are rated at 65mph, the power king info says they are STR rated which is above the 65mph ST rating. Which is it? thanks,Bob
Monday, July 28, 2014 by Gage

Are the tow max and the marathon made by the same company but just have different branding?
Saturday, August 2, 2014 by steve

I am at a cross road I have tow masters just blew 2 tires on same trip with damage to trailer I have tried several different brand tires with no luck I have an outback 29ft fifth wheel 9500# dry what do you suggest.
Friday, August 15, 2014 by AJ

dear "at a crossroads" i recommend running the load range E tires in as big a size that will fit your Outback RV trailer. also it is absolute must you run Max Pressure 80# All the Time to keep the tires cool .
Saturday, August 16, 2014 by AJ

if you must drive over 65, then buy a set of LT truck tires in load range E for your camper, that are speed rated for 100+ mph. Will cost more, but no more blow-outs .
Thursday, August 21, 2014 by Sdc

Less than 10,000 miles on my 5th wheel and already one tire failed. A large bubble, gladly found before it blew. Keep tire pressure up. Wondering if to replace or move to a different brand 16" - E load.
Friday, August 29, 2014 by Bruce

We have a 2007 traval trailer that has been sitting on a Permanente site for about five to six years now and hasn't moved. We are getting it ready to travel for next year and I am replacing the four tires on the trailer. The first one I looked at was cracked all around the sidewall so they are all going. Question: The spare has been covered and not used in all those years and still looks like a new tire. Could this tire be trusted if only used as a spare?
Saturday, November 1, 2014 by Michael Marlowe

Have a 2013 Bass Tracker, with ST-175/80r13, will the Power Kings work OK. I travel up to 500 miles one way to a Tourny.
Monday, November 3, 2014 by Gary


If your trailer calls for a 175/80R13 and will be okay with tires with 1360lbs per tire maximum load, then the Power King Towmax STR will indeed work.
Saturday, January 10, 2015 by Conrad

Do you sell a trailer tire (size ST175/80R 13) that is made in the USA?
Monday, January 12, 2015 by Gary


I know of no ST175/80R13 tires that are made in the USA.
Saturday, February 7, 2015 by Richard

I have had many tire failures on my 2012 Work & Play even after going to an E tire. I currently have two Towmax tires on the rear axel. I purchased a tire monitoring system and was wondering what would be a safe maximum pressure and temperature while in tow? I set all tires at 80# cold but this changes quickly when towing especially in hot weather. Also, would you recommend Nitrogen?
Tuesday, February 10, 2015 by Gary


As long as your are setting your inflation pressures when the tires are cold, you should not adjust them for temperatures changes. Nitrogen would offer no benefits in temperatures related pressure changes in this application.
Thursday, March 5, 2015 by Tony

I have a 2011 26 foot travel trailer that came with Goodyear Marathon 205/75/R14 from the factory. I don't see any cracks or issues yet but will be traveling from Virginia to California this summer and want to replace them to be safe. I never go above 60 mph to be safe. These are made in the USA. The new Goodyear Marathon tires are made in China. I am reading so many bad reviews of the Goodyear Marathon with blowouts and such. My current tires have about 10,000 miles on them and the tread is still good. Are the currently manufactured Goodyear Marathon tires really that bad? Thanks.
Thursday, March 5, 2015 by Gary


We have not heard of any higher instances of tire problems with the Goodyear Marathon Radial.
Thursday, March 19, 2015 by Larry

I bought 4 new Marathon ST 235/80 R16 with E load rating for my 5th wheel (9500lbs dry) in May, 2014 after two blowouts on relatively new Power King Towmax tires. They ran well for the rest of the year but now wondering if I should look into LT radials with E rating for this coming summer. What do you recommend
Tuesday, April 7, 2015 by Alan Russell

Blew 3 of these tires 3/14/15. (205/75/14) Tires were June of 2012 manufacture. All had been properly inflated for their lifetime, not over loaded. 2 Tires went within 10 miles of each other. I am guessing these tires are good for about 2.5 years before they lose their mind. Beware.
Tuesday, July 7, 2015 by TERRY ZODROW

My 5th wheel has 225/75/16 tires what size of Goodyear could I use since you don't make my size? Also which tire is better Marathon or Power King?
Saturday, July 11, 2015 by vr fortner

blew three power kings on one trip tires had less than 3000 miles on them,and yes they were properly inflated.
Tuesday, August 25, 2015 by Dave

Is this a radial or bias ply tire?
Wednesday, August 26, 2015 by Gary


These are radial tires.
Monday, August 31, 2015 by William Hulet

Well, I'm in a quandary!! I'm picking up my new 2016 Gateway 3400SE 5th wheel. It has Towmax tires. With all the bad reviews, I was thinking of going to GY marathon's but I'm seeing poor reviews on them also. So what tire is going to be best for my 12,000# (dry weight) 5th wheel? I don't want problems or damage to my new rig.
Tuesday, September 1, 2015 by Gary


As long as you are using the same tire size and load rating as recommended for your 5th wheel, you will cause no damage to it by using either brand of tire.
Monday, November 2, 2015 by Joe

I bot a '13 T/T, it has Es on the front axle & Ds on the back.
Is this safe or recomended??
Tuesday, November 3, 2015 by Gary


We do not have enough experience with mixing load ratings on trailers or RVs to make a recommendation on this, sorry.
Sunday, May 1, 2016 by kevin

What is the diferance between a bias and radial tire,and what is the best fit for car trailer
Monday, May 2, 2016 by Tire Rack Team

Kevin, The difference is in the construction and angle of the tire's steel belts. An ST tire is going to last longer that a bias ply tire and is what we offer to customers. A bias ply tire tends to have a stiffer sidewall to help keep the trailer from swaying. --
Thursday, September 15, 2016 by Jac

Hi, what is the difference between the C and D tires? I have a dolly whose tires need replacement. I'm planning to put my car on it (about 3000lbs) and tow it about 6000km with my truck. Which capacity tire for this type of dolly do I need? Thank you!
Friday, September 16, 2016 by Tire Rack Team

Jac, This will depend on the size of tire you are using. The D load range will have more reinforcement in the sidewall, so a higher load capacity in like for like tires. --
Friday, October 21, 2016 by Henry bartle

Just bought new Power King Towmax STRII ST225/75R 15 ...LOAD RANGE E/10 ...replaced 6 year old Duro tires with a load rating of C. My old tires ran at 50 max psi. these new tires call for 80 psi. my travel trailer is 30 foot with 4 tires and weighs around 9000 pounds. should I keep the psi at 80 with these new tires?
Tuesday, October 25, 2016 by Tire Rack Team

Henry, You will want to run the new tires at 80psi.
Monday, October 31, 2016 by DTR

I have had 2 Towmax ST235/85R16 LR-E Radial Trail tire blowouts on the same side of my horse trailer within 2 months. The date of the tire is 2314, which I assume is the 23 week of the year 2014. What is wrong? Are these tires defective for some reason or should I have LR-F tires on the trailer. It is a 3 horse slant and 23 ft on the floor.
Sunday, November 5, 2017 by Walt

I've been using 225/75-R15 ST E Power King Towmax tires on my 25' travel trailer for the past 7 years. Replaced the original Goodyear Marathon. The first set was replaced after 5 years, due to age (they looked fine and the at ~75% , but I was going on a 10,000+ mile cross country trip). So I am 2 years into my second set. I have had no problem with these tires. I will use the same again when it is time to replace due to age.
Sunday, February 25, 2018 by Bob

I have a 14,000 capacity equipment trailer. It currently has ST235/80R 16 load range E tires on it. I want to upgrade to load range F. Is there a problem doing this?
Also what is the speed rating for these?
Wednesday, February 28, 2018 by Tire Rack Team

Bob, you would need to check on the trailer what the minimum rated tire you can use is. The ST235/80R16 Power King Towmax STR in F load rating carries 3,860 LBS at 100 psi. Speed rating L is 75 mph.

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