tire pressure

[rperry]

2005 Winnebago Adventurer w/ Michelin 235/80 R22.5 tires.
What tire pressure is recommended for a fully loaded motorhome?
I have had several "suggestions" from RV repair facilities.

[bigbaddad]

Know your weight. If you want to plan for a bit more weight that's fine but don't exceed the gross rating (it's not just an arbitrary number) Use the tables/charts to know the pressure for your brand/size. The pressure is when tires are cold, the increase from running down the road should not be a concern. The pressure build up from running is caused by heat increase from tire flex and don't try to outguess the engineers on that. One questionable statement I often see is where people think that going up a load range in tires will allow them to use lower pressures and get a softer ride...just doing that based on tables can be dangerous. There are tires that need minimum pressures to safely stay on the rims and running pressures at the very bottom of the tables can cause flexing that raises some pretty high heat which is asking for big trouble.

[uncle_t]

a tire will lose pressure going down the road if it has a hole in it:B

[janstey58]

My MH has a sticker near the drivers seat that provides recommended PSI for front and rear tires, that I what I go by.

[crasster]

On my passenger car I always make my tire pressures about 5-7psi more than the label. It gets way better MPG and have driven this way for 3 decades with millions of miles.... On an RV I go right off the mfg suggestion to the max or tire max. One of the other. RV's are simply too heavy and large to mess around with. (Especially on my class A bounder. My little Toyota class c I've played with some on psi with no problems)

[jadatis]

Best is still to do 4 point weighing and add up to 10% to the weighed loads. Then look the needed pressure up in my made lists.

Or use my made motorhomeRV calculator.
There in part 3 you can give wheel(pair) weights and in part 2 axle weights.
Part one is to give tires and vehicle data .

The tire is allowed higher warm pressure then the given "maximum" pressure wich is in fact not even the maximum pressure , most tire makers allow 10 psi higher . So warm it can even get 30% higher then AT-pressure. So asuming the tire must not get over AT-pressure is wrong.

If you have TMPS you better switch to temperature given, and keep the warm inside tire temp about 110 to 115 degr F when driving 60m/h and no external heating like severe braking or sunshine .

Then the pressure will rise about 10% so 90 becomes 99 ( so 115 given is to high) but tombarbs given 97 becomes 105 is still about right because 97+10%$=106.7.

[Effy]

Dick_B wrote:
Crank it up to the maximum on the sidewall and go down the road happy. If the tire should lose a few pounds during a long trip don't sweat it. I start at 80 psi and will let it go down to 75 psi before adding air.

:h

Not sure if you are joking. A tire will not lose psi going down the road it will increase due to temp.

[Tom_Barb]

Executive wrote:
Over inflation will give you a very harsh ride and also cause irregular tire wear patterns.

That is exactly why you don't over inflate. Doing the TPMS experimentation will get you right where you should be at each corner of the coach.

The max pressure may not be the tire's, it may be the rim"s. our tire max pressure matches the rim's 120 PSI.

using the TPMS, we found that 90 PSI will allow the tire to heat to 115 psi, increasing the pressure to 95 the tire will heat to about 110psi. 97 psi the tire will only heat to 105. ride is good and there is no wear problems.

[dbates]

Click Here for complete Michelin RV tire how to booklet for answers to all of your tire questions. Most other make RV tires are compatible with this booklet.

Dave

[Executive45]

Glad most of these guys know more than the people that make them and the engineers that actually test them..:S...do your research.

The number one cause of tire failure is under inflation. Over inflation will give you a very harsh ride and also cause irregular tire wear patterns.

First, weigh your rig, fully loaded in travel mode. This will give you the BEST information for inflation. Next, consult your tire mfgs weight/PSI tables. Click HERE for your mfg inflation table.
Remember to inflate your tires to the same pressure across each axle. That is, take the highest listed pressure and inflate both steer tires to that pressure and do the same with your drive axle using the highest weight on each axle. Remember, WEIGH your rig first. Flying J/Pilot, moving companies, grain elevators, lots of places to weigh your rig. Your local yellow pages will locate the one closest to your home...Buying a TPMS is a good idea but they have absolutely nothing to do with determining the correct tire pressure you should carry in your tires. only your WEIGHT and the corresponding correct table can determine that......good luck...Dennis

[Dick_B]

Crank it up to the maximum on the sidewall and go down the road happy. If the tire should lose a few pounds during a long trip don't sweat it. I start at 80 psi and will let it go down to 75 psi before adding air.

[Ivylog]

"Buy a TPMS, and set the pressure by it." About all I can say is this is a first. Actually I have a lot to say as I do not see this as a better way. Yes, running more pressure than needed will not hurt the tire and will decrease the pressure/heat increase which is normal. If you look at the sidewall of your tire it will say XXX max press COLD. Pretty sure Goodyear knows the pressure is going to increase when the tire warms up, even going above the max pressure... so what? It's no longer a cold pressure.
I do run 5 psi more than the inflation/weight table because I'll still drive when there is a strong cross wind. It can shift enough weight to the down wind side so I see more than the normal 10% increase in tire pressure.

[Tom_Barb]

wolfe10 wrote:


Longer term answer is get it weighted and set pressures accordingly.

There is a better way.

Buy a TPMS, and set the pressure by it.

We found that running with the pressure at the suggested pressure by weight caused the tires to heat and go over the recommended max pressure by the manufacturer.
We increased the pressure, and found the tires did not heat as much and stayed under the max pressure.
So we increased it more and found it heated less, did it again, no change, and that is where run our tires. 10X22.5 Michelins at our load 97 pounds is where we run. recommended pressure was 90.

[ed6713]

Plus. Look at the tire sidewall.you will see a max. cold inflation pressure. Don't exceed that number.

[wolfe10]

Tire pressure/weight tables are set up for actual weights.

If you are close to your axle's GAWR, then use the PSI recommendation on the plaque likely near the driver's area that lists GAWR's, tire size and PSI.

Longer term answer is get it weighted and set pressures accordingly.