Hi all,Have a question about tires..Tires are hot at 80, 82 psi returning from cold mountain trip thru local desert, traffic and home. Rear tires noticably hotter than fronts and had a smell like hot rubber. Posted are the weights on the axels for my 23u thor. I notice I'm about 700lbs below the limit of the rear axle. Usually that axle is loaded about 600 lbs lighter. No smell, not so hot.Is there a danger? Factory michelin tires, 2016 date. Don't recall smelling this. Tires not painful hot but hot. Touched the rims, axle shafts..not the source of heat. It's tire flex. This is the most I've loaded this. E450 chassis, 2017 model 14,000 gvwr. Usually carry a 300 lbs motorcycle on back never a worry. This time a 470 lbs bike and about another 50lbs lbs for the more stout rack tying into frame.Any thoughts?Thanks Cb

Our 31' has a lot of extra weight on that rear axle regularly so we go overweight regularly so we need to keep them at the max 80 psi. Never noticed a smell but we watch the speed on hot pavement, sometimes even deliberately choosing to drive early/ late.

I wouldn't be worried. If one tire were noticeably hotter than the others it would be good to give that one some scrutiny as it may be low or delaminating internally or something; but tires generally getting quite warm in use is normal. (I'm assuming the cold inflation pressures are correct for the weight they're carrying; pressures when they're hot will of course be higher per the ideal gas law.)I highly suspect the smell comes from something other than the tires.

Congradulations you have the first step to setting the correct tire pressure. Go the the tire mfg load inflation table for your tires and set the tire psi per axle per given weight when cold as indicated. Weight is based on fully loaded, full fuel, water and propane.Example: My steers are set to 120psi and duals to 90 psi based on axle weight and 2 vs 4 tires on the axle, same tires.Max psi is used when you don't know the weight or think you know more than the tire mfg. I've seen 140F internal tire temps, just keep on trucking.

I've already done the math. I set off at 76 lbs, came in at 82, 83 lbs??

"Weight is based on fully loaded, full fuel, water and propane."Not sure what you mean... Weight is weight regardless of how you get there. Our E-350 with a GVWR of 11,500# can be anywhere from 10,000 to 11,500 depending on how I am loaded and/or towing. Weigh the coach loaded as you normally travel and then set your psi based upon the tire manufacturers load/inflation table. The weights shown on your door jamb are rarely accurate in the real world.Depending on your tires load rating {D, E, F whatever} your tires may be quite capable of handling their actual loads and still be well under the max psi found on the sidewalls. Max Psi and door jamb numbers might maybe be accurate occasionally but never assume them to be correct without knowing the load each tire is actually carrying.Just sayin...:C

Question about tires..smell? Temp? | Good Sam Community

hujarine
Explorer
Oct 09, 2021
I feel it's normal for tire to be hot after a long distance journey. Though most times the front tire is always hotter than the rear tire especially if it's a motorhome. But I guess the reason the rear is hotter than front in your case may be due to overload. I don't think it should be anything serious.
cbigham
Explorer III
Oct 06, 2021
DrewE-
That's what I figured. Using K for units P1v1/t1=p2v2/t2 assuming minimal or no tire volume expansion. It's the smell.. I cannot find any bulges, delam as I normally see on tires about to lose it. (No need for n, R in formula to compare temp to temp)

thanks
DrewE
Explorer II
Oct 06, 2021
The 5 psi gain suggests that the air temperature in your tire increased by very roughly 17C or 30F -- perfectly reasonable.

(That's based on the ideal gas law: PV=nRT, or pressure * volume = quantity of gas * ideal gas constant * absolute temperature. In the case of a tire, the volume and quantity of gas don't change appreciably, and of course the ideal gas constant is also constant. Hence, the change in (absolute) pressure is directly proportional to the change in (absolute) temperature.)
cbigham
Explorer III
Oct 06, 2021
No, thanks.
I did the calcs before putting the bike on. Scale reading is with bike, rack on. The 82 degrees is hot, just in from the road. Readings were 77 prior to.
4x4van
Explorer III
Oct 05, 2021
2 quick thoughts; based on your weight ticket, you have only 660 lbs available on the rear axle; if you added the bike after that ticket, then your axle IS overloaded. Also, is that 80-82 psi that you referred to the cold pressure (before driving), or is that the pressure after driving and when the tires were hot?
cbigham
Explorer III
Oct 05, 2021
A lighter bike, sure, we do on occasion carry son's bike there. Then you have issues of blocking radiator if bike big, and headlights. I calculated the 790r with rack puts about 1100 on the hitch when accounting for the center of gravity is about 3 ft or so further from the hitch. The rear is reinforced with 3 receivers, 2bon the frame rail, and the center hitch. It's all very heavy duty and reinforced.
Front, no.
Holiday27
Explorer
Oct 05, 2021
Maybe placing the bike up front might help? I've had smaller bikes up front but a big bike could block some of the view so not sure.
cbigham
Explorer III
Oct 04, 2021
phillyg wrote:
Nothing to be concerned about IMHO, but you should invest in an infrared temp gauge. My rears will always show higher temps when pulling my fiver.

Your number, ratio is about what I calculated. I'm still under the 9600 lbs rear axle weight. That's the factor, tho this is the most weight I've had on the rear axle which likely is.
noteven
Explorer III
Oct 04, 2021
c'mon up to west Canada and Alaska for the next 6.5 months.

Tire heat will cure its own self.

I know, not helpful.
phillyg
Explorer II
Oct 04, 2021
Nothing to be concerned about IMHO, but you should invest in an infrared temp gauge. My rears will always show higher temps when pulling my fiver.

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