Tire Pressure Question

[JudyJB]

I have a 15,000 lb (loaded weight) 32' 2012 Class C that I have driven for 25,000 miles. I get my tires checked every month or two. I just got an oil change, RV wash, and a tire pressure check last week in South Dakota. (Altitude about 4,000 feet and temps in low 90s that day.) In the past, to my knowledge, the dealer and the factory filled the tires to the rated pressure of 80 PSI. I always ask about any tires being lower than that because I want to know if one tire is slowly losing air.

As I left, they notified me that the tires were fine and that they had set the pressure at 70 PSI because they worry about the temperature and the tires (especially the rear duallys) getting hot in the summer. I accepted this, but it has been worrying me. I have not yet called the factory, however. I am in the Black Hills and headed into Yellowstone, the Tetons, and Glacier, all of which are at higher elevations.

The oil change place specializes in big truck maintenance and washing, and handle RVs along with big rigs and commercial vehicles.

What do you think about this advice? I am going to call the factory on Monday, but I wondered what the rest of you do.

[Bethers]

You shouldn't be filling to the "rated" pressure on the tires. You should be filling to what it says in your manual and on the inside of your door - often much less than the rated pressure. And usually on a Class C it'll be different on the back tires than the front tires. You should find and know what the tire pressure should be for your vehicle - again NOT what it says on the tires.

That said, yes, temps can make a difference - but I'd go look to find out what is recommended for your vehicle.

[sharon]

There should be a graph in your manual showing tire pressures at different loaded weights. Beth is right, the pressure on the tire is the max allowed pressure, not what is recommended by the rv manufacturer. The manufacturer has worked with the tire manufacturer to figure out what the tire should be for maximum safety and longevity.

[grammynmaggie]

I was told by many ...techs to set at 75 (calls for 80) to allow for
expansion while driving...tires worried me a lot ...not so much now
as I learn more...donna

[BirdbyBird]

I had been taught that the psi that is listed on the door of my rig was the "cold" pressure reading and took in account that the pressures were going up as soon as I drove down the road any length of time. The recommendation is that the tires get checked in the morning before you move the rig. I have had to readjust pressures from winter driving and summer driving because the temps in Ohio are so different in the different seasons.... I also have a pressure monitoring system which can give peace of mind or just remind you to worry at the changes more as you drive down the highway....

[sharon]

I had been taught that the psi that is listed on the door of my rig was the "cold" pressure reading and took in account that the pressures were going up as soon as I drove down the road any length of time. The recommendation is that the tires get checked in the morning before you move the rig. I have had to readjust pressures from winter driving and summer driving because the temps in Ohio are so different in the different seasons.... I also have a pressure monitoring system which can give peace of mind or just remind you to worry at the changes more as you drive down the highway....

True....

[Bethers]

Right about cold pressure - and you really should only be reading your tire pressure when cold.

I remember when Jean needed a tire fixed. I asked if they'd check my pressure. They had fixed her tire and then told me it would be another 1/2 hour before checking my pressure- good tire place - they wanted to be sure my tires were "cold" after the drive there. (It's also the place that put on/replaced my valve extenders for free).

[WickedLady]

This is from Escapees: Tires should always be inflated to the desired pressure when "cold" otherwise known as current ambient temperature. You should not "allow for expansion" when setting pressure. The pressure increase while operating is factored in by the tire manufacturer when the tire is designed. All tires have a maximum inflation pressure stamped on the sidewall. You should not exceed that pressure when adding air to a cold tire, but you may safely inflate the tire all the way up to the max pressure on the sidewall. However, that may be more pressure than is needed, based on the actural load on the tire.
All of the major tire manufacturers offer tire load/inflation charts that tell you what the proper inflation pressure is for a given load for your specific tire.
Check out www.escapees.com/smartweigh

[Bethers]

That Excapees reply is a little confusing and slightly wrong ... in that you still do NOT use what's on the tire to decide what to inflate to. That is the maximum those tires CAN be inflated to. A link on the Escapees site took me to better info - hopefully explaining more of what I'm trying to say - this is from Goodyear regarding rv tires:

"Correct tire inflation is a key component in tire care. The recommended maximum inflation pressures for your tires are indicated on the certification label or in your owner's manual. Since RVs can be loaded with many different configurations, the load on each tire will vary. For this reason, actual air pressure required should be determined based on the load on each individual tire. Inflation pressure should be adjusted to handle the tire carrying the heaviest load, and all tires on the axle should be adjusted to this standard."

Notice that the maximum you should inflate to is what's in your owner's manual - NOT what the tires can safely be inflated to. (Or your certification label, which is most often found inside your driver's door).

For all the information on Goodyear's page: http://www.goodyearrvtires.com/tire-inf ... ading.aspx

And please don't think I'm saying anything negative about Escapee's - just in this case they worded things confusingly and a little misleadingly.

[grammynmaggie]

tires have been my nemesis for since I got my RV very confusing
it almost sounds like I need to get my RV weighed everytime I put air in the tires.. how do I know how much weight is on each tire?
I've been thinking about when I have to pack up to return to Florida how do I put things in the RV to distribute weight this question is for another post which I will do it's just that now this tire thing is making me more confused....