Digem

What's the difference in a 235/75/15 vs. 235/70/15

Lowrance

235/75/15 is taller and holds the weight of the truck. The 235/70/15 won't safely hold the weight and load of the truck.

Crownman

Saying that WON'T safely hold the weight of the truck just because of that small of a change in aspect ratio is crazy. It will safely and easily hold the weight.

Digem

The difference in those two tires is there a majorly big difference in size/width?

Lowrance

Incorrect and check the math sir. The vehicle will hold the weight of the truck but not the reserve load. My truck (96 xcab) comes OEM 235/75/15 and clearly states XL(Extra load, with a load index of 108) with an inflation of 41PSI front and rear. The 235/70/15 in MOST cases is 100 load index, with a standard load designation. If you look at an inflation table of standard load and extra load, there is NO possible way a standard load 100 load index can meet or exceed the weight of a Extra load 108 load index at 41PSI. Do the research before saying its crazy.

tvand13

235/75R15 = 28.88"x9.3"
235/70R15 = 27.95"x9.3"

I agree that both tires would be perfectly safe on your truck.

Lowrance

I'll just leave this load index chart here. It shows the maximum weight a tire can safely carry for a given index. 108 carries a maximum of 2205, 102 carries a maximum of 1874. While the tires may support the weight of the truck, they won't meet the "reserve load: when the truck is fully weighted down to its advertised capacity" And while your next argument will be that you never load the tire down, from a liability perspective if the tire fails due to under/overloading, the tire shop and vehicle owner are responsible for the improper fitment. Remember the major lawsuits from the Explorers? Some of those lawsuits were due to improper fitments because somebody said it was ok without fact finding. It's your vehicle, do what you want. But remember that it's your responsibility to keep yourself and the other people on the road (who had no decision in whether or not you put the right tire on your truck) safe.

Digem

Goodness I'm so confused now.

Lowrance

PM'd

billt460

My 1991 F-150 XLT Lariat 2-WD 5.0 came with P235 X 75 R15 passenger car tires. They weren't even light truck rated. They looked stupidly small and out of place on the truck, and went south after only about 20,000 miles. After that I went with 31 X 10.5 X 15's, and the truck looks and rides much better. They are a bit larger in circumference and I've noticed it's down on power. But it's been down on power since the day I bought it! I'm on my third set now with 150,000 miles on the vehicle. With my Air Shocks at a full 90 PSI the top of my camper shell clears the top of the garage door by about an inch and a half.