Community Forums

Brad Felmey · 05-27-2016, 12:38 PM

In watching my TPMS system (EEZRV, if it makes a difference) I see that the front tires get much, much hotter than the rear ones do. I just returned from a short (20 miles) trip with mostly in-town driving, and the front tires were between 124F and 140F, while the rears were around 90-100F. The ambient temperature is about 70F.

I know that the front tires are carrying more weight individually than the rears, and that the front brakes are responsible for a majority of braking, and thus have more friction.

I don't know what an appropriate amount of heat is. The TPMS system recommended just a flat 156F alert threshold with a 20% over-inflation alert threshold (this equates to 96psi in my 80psi tires). I didn't reach those numbers (pressure topped out at 90psi), and indeed the temperature decreased on the stretches that were on the highway and not stop-and-go 45mph.

I just want someone to soothingly tell me that I'm worrywarting for nothing.

BFlinn181 · 05-27-2016, 01:28 PM

How hot was the roadway? Did you do lots of braking? Have you weighed the RV and adjusted the tire pressures for the weight the tires are carrying? Sunlight also has a big effect on tire temperatures.

Pepper2 · 05-27-2016, 01:45 PM

Only answer I can give you is associated with highway driving. Just returned from a trip and the sunny side of the MH tires were at about 101. Didn't notice a difference between front and rear, just sunny/shady side. Ambient temp. was 84. Hope this helps.

**Lt Dan** · 05-27-2016, 01:54 PM

Brad, as BFlinn said have you weighed the front of the coach to set your pressure correctly for the weight? 80psi sounds kind of low for a front, but if it's light that may be okay. As for temperature, I've never seen higher than 105-110 degrees on the highway in 90 degree weather for several hours. 30-40 degrees hotter than your rears in 70 degree weather in only 20 miles sounds a bit high, but the tire experts opinions may differ. An underinflated tire will flex more and build up more heat than a properly inflated tire.

Old Scout · 05-27-2016, 02:03 PM

Seems like my TST system has a set high limit set at like around 160--based on industry std for tires in general. Have no idea what the pressure in the front tires for you rig should be but 80PSI seems low for single axle tires. Too low a pressure would certainly create excess heat.....

windsorbill · 05-27-2016, 05:11 PM

Quote:

Originally Posted by Brad Felmey

In watching my TPMS system (EEZRV, if it makes a difference) I see that the front tires get much, much hotter than the rear ones do. I just returned from a short (20 miles) trip with mostly in-town driving, and the front tires were between 124F and 140F, while the rears were around 90-100F. The ambient temperature is about 70F.

I know that the front tires are carrying more weight individually than the rears, and that the front brakes are responsible for a majority of braking, and thus have more friction.

I don't know what an appropriate amount of heat is. The TPMS system recommended just a flat 156F alert threshold with a 20% over-inflation alert threshold (this equates to 96psi in my 80psi tires). I didn't reach those numbers (pressure topped out at 90psi), and indeed the temperature decreased on the stretches that were on the highway and not stop-and-go 45mph.

I just want someone to soothingly tell me that I'm worrywarting for nothing.

Brad,

I'm in agreement with everyone else. You should weigh your coach, each corner is best, but each axle is what most people do, and adjust the tire pressure to the weight on each axle. You can go on the web and download your particular tile manufacture pressure chart. Don't go by the placard in your motorhome (if you have one). An under inflated tire will heat up very quickly and shorten the life rather dramatically, not to mention the risk of a failure.

Alan_Hepburn · 05-27-2016, 05:19 PM

The TST system comes preset with a max temperature in the 180 degree range - apparently that's where the rubber compound in the tires starts to break down...

Mr_D · 05-27-2016, 05:20 PM

Quote:

Originally Posted by Old Scout

Seems like my TST system has a set high limit set at like around 160--based on industry std for tires in general. Have no idea what the pressure in the front tires for you rig should be but 80PSI seems low for single axle tires. Too low a pressure would certainly create excess heat.....

My TST instructions say 158°.

mhbell · 05-27-2016, 08:27 PM

There are a lot of factors involved. Road Temp, Axle and Bearing Temps, Tire pressure, amb temp, weight of veh on tires. Get a Non Contact infrared thermometer with laser targeting. (Harbor Freight) sells them. I use one at every rest stop. I check the hubs (Bearing temp) as well as the tire surface. Dragging brakes, Bad Bearings, or excessive use of brakes can cause the temp to rise on the TPMS. The TPMS can't tell the difference of what is causing the problem. That has been my experience. I use the same TPMS and ignore the High temp setting and depend on the Infrared temp gun.
Mel

Coma · 05-28-2016, 12:47 PM

I see 125-127F in the summer, all six tires.

Old-Biscuit · 05-28-2016, 01:05 PM

Infrared temp gun works.....key is take temp at same distance in same spot for better temp readings and trends

I have seen 135*F on rear truck tires in 100*F air temps towing at max load rating of tires
Same time.......trailer tires were 115*F

I'm not too concerned with actual temps but I watch for 'trends'.........one tire running higher than companion tire (or hub/rotor etc)
or that one wheel/tire position increasing in temps over period of time

Big Dude · 05-28-2016, 01:15 PM

Like others have said - you may need a higher pressure. I had a 96 HR Imperial and ran either 90 or 100 psi in the front - can't remember for sure.

Gary RVRoamer · 05-28-2016, 01:53 PM

Mine run around 115 or so in hot summer driving.

Your temperatures aren't too high in an absolute sense, but it would worry me that the fronts are so much higher and when the rears are running cool. That's a lot of degrees for a short ride in moderate summer weather. My first thought would be that the fronts are under-inflated. If not, then maybe dragging brakes or lack of bearing lubrication?

Gdawgs · 05-29-2016, 06:37 AM

Brad,

I run 105psi on the front and 85psi on drive axle and tag. Temp. runs about 90-100 degrees this time of years with outside temps in the 80's. After about 20 miles front pressure rises to about 115 and rear to about 95. Temperatures remain in the 90-100 range. Like others have suggested I'd add a little more air to the front and check to see how the tread is wearing. Outer tread wear indicates under inflation. take care.