Are trying to get a tire with a taller sidewall on your current wheels for better ride quality? Or are wanting a bigger tire to give your truck or SUV a more aggressive look? Whatever your reasoning is, you want to make sure the bigger tires you want will fit on your vehicle without causing any problems. We may not be able to guarantee the fitment on a larger diameter tire, so you may need to do some measuring of your own and decide for yourself what tire size you want.
The first possible problem with larger diameter tires is the speedometer calibration. Your vehicle calculates your current rate of speed based on the factory tire diameter, so if you put a bigger tire on it, the number of revolutions per mile decreases and that will make the speedometer read slower than your actual speed. The amount it varies is a percentage, so remember to calculate your actual speed correctly. For example, if you start with a 29-inch tall tire and you go up to a 32-inch tall tire, then your speedometer will be off by about 10%. That means if your speedometer reads 50 mph, you're actually traveling at about 55 mph. Many dealerships can reprogram your vehicle's CPU to adjust the speedometer for tire diameter changes, or there are many aftermarket options for reprogramming vehicles.
The second, and probably most important, problem with larger diameter tires is determining whether or not they will fit. Sometimes we will be able to tell you that a specific tire size will fit, but we often can't guarantee it if the tires are significantly larger than the Original Equipment tires. In that case, you'll need to either do some internet research or go out and measure the clearance yourself. To check to see how much clearance you have, make sure you pay special attention to the front, as that's where the turning happens. You will want to turn the wheels all the way to the left and right while inspecting the areas around the entire tire. If possible, do this while also articulating the suspension up and down in the wheel wells to make sure you won't have rubbing when you hit bumps or turn sharply. It may look like you have all the room in the world while it's parked in the driveway, but when you turn the wheels and compress the suspension up into the wheel wells, a lot of that room goes away in a hurry.
As a final note, remember that bigger tires usually come with more weight. If the difference is significant, that can affect other things, including, but not limited to, added wear on parts, acceleration, handling and fuel mileage. For more information on how to calculate your tire size, read "Light Truck Fitment Formula."