What Should The Minimum And Maximum PSI Settings Be When Setting UP TPMS?

Updated 09/23/2026 | Published 09/20/2026

Question:

TST-507-RV-4-C .... Pardon me for asking you your opinion. E-Trailer has been good with me multiple times when I was sourcing parts for the Ford dealer that I used to work for, buying a few items through you for my personal use, such as my axxess half tonneau cover for my truck. However, I have the TST 507 that came with my camper when I purchased it new. I am running 12 sensors 6 truck and 6 trailer for my triple axle. My tire specs are 110 psi cold - what is your advice on setting the tire pressure min and max on the TPM unit? Thanks in advance.

asked by: Chris D

Expert Reply:

Welcome back Chris!

When setting up TPMS minimum and maximum pressure warnings, I use the 20-20 rule. That's 20% lower than the cold PSI for the minimum and 20% higher than the cold PSI for the maximum. So in your case, I would set 88 psi for the minimum and 132 psi for the maximum in your case. There are other opinions with this kind of thing, of course, but I have found this to be a pretty foolproof way to do it.

What kind of trailer are you towing?

expert reply by: Lazer S

Chris D.

9/21/2026

Thanks for the reply. I have a 2023 F450 with a 2025 Keystone Raptor 428 TH. Gross weight rating for the trailer is 20K. I've recently experienced, after about 25 minutes of towing in near 100* St Louis weather, that one tire seems to shoot over my alloted 135 psi threshold (when I set it to 120 psi as per the tire). I recently learned that the specs for this unit is 110, so I lowered everything by 10psi - including the warning threshold for the TST. On my next trip, I still received a warning as I was too high. Interesting fact that it was always the left middle tire. To be fair, the other tires were about 3-5 psi off from that tire, so I doubt that I have a mechanical issue. Got any insight about that? Now I'll need to wait until next year for 100* temps, but I'll reset my threshold pressures as you suggested.

Lazer S.

9/23/2026

@ChrisD We are headquartered in Wentzville, so I feel your pain with the heat. Hopefully we are actually getting into fall now, but as we all know, Missouri can have several false falls (insert heavy sigh here). But with it being just the left middle tire that is heating up more than the others, make sure you have the wheel greased properly. Also make sure your suspension components are well greased and in good working order. With your Keystone being a 2025, that should all be fine, but it never hurts to check. Have you noticed and odd wear on that specific tire?