131psi high alarm

[d2reid]

I love my TPMS. It gives me all kinds of data. Years of playing with tire pressure and driving conditions I have learned a lot about tire pressure. Silly stuff like tire pressure is recommended at 70F. That you can adjust 1 psi per 5 degrees F. So starting out on this run it was 50f out, so I set my 110psi tires to 106 psi balanced on all tires. Then the run begins, 325 miles today, psi was running 125-128 most of the day, IMHO, perfect. Then 10 miles from my destination my left front pops a high pressure alarm, 131. 110-131 is a big increase. Why? I check the brake and hub temps, under 100f. Hmmmm!

Other tires were keeping in the 125-128 range. What's going on? I know these kinds of variances are fairly normal, but this divergence in PSI is a harbinger of trouble. I know better than to adjust tire pressure when the tires are still warm off the road so won't make any adjustments tonight. I will check them first thing in the morning to look for variances per tire. Why did the left front go High? Probably nothing, but I got my eye on it....

[TedS]

Maybe alignment changed and the tire is scrubbing more. Watch the tread wear for clues.

FWIW: quit fussing with cold tire pressure. Pressure change is about 1 to 1.5 psi per 10 deg F. Underinflation will generate more temperature change than overinflation.

[TucsonJim]

Driving in the heat of Arizona, I see some crazy changes in PSI when driving. Frequently, my tires on the sunny side will register a higher PSI than the shady side. But other nefarious reasons such as an overheating wheel bearing or dragging brake can cause temperature and PSI increases also.

Here's how I'd approach it:

Purchase an infrared non contact heat gun such as the one linked below.

When you stop for a break, check the temperature of the wheel hubs, tires, and brake drums. If any one of them is significantly different from the others, further investigation is warranted. And of course, if you start to see one tire deviating from the others on your TPMS, pull over and check the temps with the gun to see if anything else needs to be done. I wouldn't get too concerned unless one of the wheel positions is showing a difference of more than 10°F.

https://www.amazon.com/Klein-Tools-I...534531&sr=8-16

Jim

[d2reid]

quit fussing with cold tire pressure. Pressure change is about 1 to 1.5 psi per 10 deg F.

I think you are more correct than I on the temperature variance. I was using 1 psi per 5 degrees F. 1 PSI per 10 degrees F sounds more reasonable. I will always fuss about cold tire pressure. It's how I start my drive knowing all tires are relatively even PSI, then watch the changes throughout the day to get ahead of possible problems.

Todays run started at around 105 PSI, it was 42F. All 6 ran 125-128 all day long, no high indicators.

Purchase an infrared non contact heat gun such as the one linked below.... I wouldn't get too concerned unless one of the wheel positions is showing a difference of more than 10°F.
Jim

I have one, I use it to check hub temps. My disk brake system allows fairly easy access to the hub walls. I also shoot the disk face. Typically 95-125F. After new bearings were put in I say 275F, but within a couple of hundred miles those temps started to drop.

The 131 was only about 5F above the rest, resulting in a TPMS alarm, next day, no alarm.

Today's run had some 30-40mph crosswinds, perhaps yesterdays the wind was coming from the side, causing the right side of the RV to get more weight than the left side. Today's wind was right up the tailpipe, perfect, even psi on both sides.

[Guest]

Dallas,

New wheel bearings if installed properly should not exhibit higher hub temperatures. I would be very suspicious the bearings were too tight upon installation. Bearing preload is accomplished by torquing to 50 ft lbs and without rotating the hub, back off completely then tighten finger tight (no tools) and capture the nut with the cotter key or locking washer or other device. This method sets the proper clearance to allow for lubricant to coat all the running surfaces.

Jim

[d2reid]

Dallas,

New wheel bearings if installed properly should not exhibit higher hub temperatures. I would be very suspicious the bearings were too tight upon installation. Bearing preload is accomplished by torquing to 50 ft lbs and without rotating the hub, back off completely then tighten finger tight (no tools) and capture the nut with the cotter key or locking washer or other device. This method sets the proper clearance to allow for lubricant to coat all the running surfaces.

Jim

Sorry, boondocking and off line for a few days.... I have replaced a number of bearings in my life. Granted, I had no engineered/scientific method of doing so. As a result I have observed that new bearings tend to run warm until they are; forgive the inaccurate terminology; seated.

I will admit that the issue is due to improper installation. Redneck with a wrench, should not be allowed out in public. It's amazing I get down the road as many miles as I do. All 6 of my current hubs are running 90-120F external temps. They are new as of February 2020. Only about 10k on them as Covid has really slowed us down.

[Guest]

Dallas,

Good ol boys live up north too. Many times folks will feel the play in the assembled wheel and will not feel comfortable with this and will tighten up where no play is felt. There is unintended risk is doing this.
Assembling the bearing nut finger tight will result in some play when rocking the wheel side to side. When the hub heats up, the clearances will tighten up and will be perfect for proper lubrication.

Jim

[d2reid]

Dallas,

Good ol boys live up north too. Many times folks will feel the play in the assembled wheel and will not feel comfortable with this and will tighten up where no play is felt. There is unintended risk is doing this.
Assembling the bearing nut finger tight will result in some play when rocking the wheel side to side. When the hub heats up, the clearances will tighten up and will be perfect for proper lubrication.

Jim

Contrary to common belief I do learn from my mistakes. So after a bunch of fails my process was to tap the new bearings in with lots of grease, tighten the nut until the wheel would not spin, (this would ensure the bearings were fully compacted in place), then back the nut off 1/4 turn until the wheel would spin freely. Insert cotter pin.

I am sure there are lots of engineering pit falls to that process, but it worked for me.

[Guest]

Contrary to common belief I do learn from my mistakes. So after a bunch of fails my process was to tap the new bearings in with lots of grease, tighten the nut until the wheel would not spin, (this would ensure the bearings were fully compacted in place), then back the nut off 1/4 turn until the wheel would spin freely. Insert cotter pin.

I am sure there are lots of engineering pit falls to that process, but it worked for me.

Dallas,

I've read your posts and think of you as a pretty smart fellow. But only because I do not want to see you or others to have problems in using this method, I'm just letting you know, this process will eventually fail. I'll move away from this discussion where I hope you adopt the accepted method or at least carry a spare hub assembly.

Jim

[d2reid]

Dallas,

I've read your posts and think of you as a pretty smart fellow. But only because I do not want to see you or others to have problems in using this method, I'm just letting you know, this process will eventually fail. I'll move away from this discussion where I hope you adopt the accepted method or at least carry a spare hub assembly.

Jim

Yup, pretty smart. That's why I no longer do my own bearings. A man has to know his own limitations. Fortunately I am no longer in the situation that I have to rely on my own ignorance.