Recommended Tire Pressure When Using Different Size Tires than the Factory Tire Size

Question:

I just changed tires from 270/65r18 to 255/70r18 and am trying to determine the best tire pressure. I have a 2011 Toyota tundra and the specs said that the 270/65/r18 tires should be front 30psi and rear 33psi. My question is what should my psi be on the 255/70r18 tires?

asked by: Cory J

Expert Reply:

For your vehicle tires, the max psi should be listed on the sidewall of the tire. With vehicle tires, the recommended psi is listed. This should be used instead of your vehicle tag since you have changed tire sizes form the OEM tires.

Inflation values on vehicle tires (passenger tires specified with a P before the tire size) are different from those on a trailer (Special Trailer designated ST prior to the tire size). Trailer tires are made to be run at their max PSI at all times, where passenger tires have a recommended psi and a max psi not to be exceeded based on how the tires are designed.

Based on your wheel size, you must have passenger tires as 18 inch wheels are not one of the standard trailer wheel sizes.

expert reply by: Jason S