Rapid rear tire pressure increase when towing

When towing I've noticed my rear tire pressure jumps about 5psi more than my front tires. front and rear start at the same cold pressure. This has happened several times now.

Is this normal? 5psi more than the front seems like a lot. tongue weight is probably around 400lbs.

 

It’s normal. You’re putting more load in the tires so they heat up faster.

 

5 psi is nothing to worry about.

Two strategies if you must worry about it.

1. Raise the starting pressure and you will get a smaller pressure rise. A tire that flexes less will build up less heat and therefore have less pressure rise.
2. (and I don't recommend this) lower the pressure, accept an even bigger pressure rise and arrive at your desired end pressure during operation.

My method is to set the hardest tire pressure that rides acceptably, and then check the tire temps after an extended freeway run. Tires should not be hot to the touch unless you're on a race track.

 

I've always run max. pressure with no wear issues. Our 100*+ summers here in central Ca. raise pressure but an add on TPMS has not only pressure shown but setable heat, pressure and rapid pressure loss alarmed parameters.