AskTFL: Do Aftermarket Tires Affect Your Tow Rating? Here is How To Check (Guide)

Looking at upgrading your truck’s tires to something from the aftermarket is the first step to making your rig better in the dirt, but how will that affect your tow rating? 

We received this question from a reader who is looking to upgrade to a set of 35-inch BFGoodrich K02s or Goodyear Wrangler Duratracs on his 2016 Ford F-250, but is worried that it might adversely affect his payload and tow ratings.

For the answer to this one, we reached out to BFGoodrich directly and got an answer back from a BFG engineer, and you can read it below.

“It all depends on the load index of the tire that came on the vehicle from the OEM vs. the load index of the tire the customer wants to upgrade to.  We recommend installing a tire with equal to or higher load index than the tire that came on the vehicle from the OEM.  While more information would be needed to fully answer his question, we can say that if the tire size is LT245/75R17 and if he wants to go with a 35×12.50R17, then this is doable and the load rating / tow rating of the vehicle isn’t affected.

Fun fact – The load index are the numbers following the tire size and indicate the load carrying capacity of the tire.  The higher the number, the higher the load the tire can carry.  If you see two numbers (121/118 for example), the first is for single tire use, and the second is for dual tire use (like dually pickup trucks).”

BFGoodrich All-Terrain T/A KO2 LT245/75R17/E 121/118S
BFGoodrich All-Terrain T/A KO2 35×12.50R17/E 121R


So, the basic principal to remember is that it’s all about load index, and to make sure that the load index on your new tires is equal to or greater than the set that came on the vehicle originally.

The tire load index for passenger cars and for light trucks ranges from 70 to 126. On the low end, a load range 70 tire can support 739 pounds, while a load range 126 tire can support 3,748 pounds. When it comes to figuring out the load capacity of the tires on a vehicle, you simply take the weight rating of one tire and multiply it by four. That means a vehicle with 126 load range tires can support 14,992 pounds in total.

So if you’re looking to upgrade your rubber, pay attention to the load index rating and you’ll be good to go!

Here is how our project Hummer H2 performs before and after a set of BFGoodrick KM2 tires.