my tires are now all the same 7 lbs under what i want but I know that this after noon they will be what I want and 30 deg warmer should I leave them alone I an leaving in 3 hours just want to know now
anxious lenny

From my experience I would leave them be until your first fuel stop or rest stop. I'd bet they'll be up to full pressure. This happens to me at Talledega when we leave in the cold on monday morning. All my tires read 10 lb. low, but by the first stop they are right where they should be. If one is lower than the rest, then equalize it, but if they're all a little low, it's the temp. Anyone out there that wants to correct me, feel free.

quote:

Originally posted by Danny Z:
This happens to me at Talledega when we leave in the cold on monday morning. All my tires read 10 lb. low.

Wow, that's a lot. Army rule of thumb used to be pressure drops 2 psi for every 10 degrees F. Goodyear says that, too. http://www.goodyear.com/truck/...erv/Retread_S5_V.pdf

The same site says. "Always inflate
tires cold to the required pressure no
matter what the ambient temperature is."

Most tire manufacturers recommend that tire pressure be set in the morning when cold and before driving, never reset your pressure when hot or you will be under-inflated and if the pressure is correct when hot, it is in fact under inflated. If the tires have been in the sun for awhile, then the pressure will read higher, but again, the pressure should be set before any outside influence has caused the pressure to increase.

I always check my pressures before I start out in the morning and as long as my "bong" test and visual inspection shows no concern, I will not measure/reset the pressures until the next period of inactivity when the tires will be cold. If extremely cold outside then the pressure should be reduced by 1 PSI for every 10 degrees below "standard day" temperature. IIRC "standard day" temps should be 60 degrees F. so at 50 degrees, you should set only 1 PSI lower for the weight load on that particular wheel. You are correct Bill.

Under-inflation is far worse then over-inflation!

Some reading:

from Tirerack

I'm with Ed. Correct pressure before you leave.

Once again, I stand corrected by those with more knowledge than me .

Here in south florida tires can be 5 to 8 lbs. light when you check them in the morning.I get worried when they are 10 lbs. below but after the first stop which is 35 miles they are right up there within 1LB.the temp last week was 85 inland one day and and 37 2 days later.DID a bunch of my fruit trees in. CAN YOU DRIVE THIS THING WITH TIRES 10 LBS LIGHT WITH OUT HURTING THEM?I CHECK MY TIRES ONCE A WEEK AND THEY CHANGE THAT much.
sorry about the caps.The tag above my head says 95lbs cold but how cold
LENNY

Tires deal better with over inflation than any degree of under inflation. Inflate them to spec in the AM & don't worry about the rest of the day.

The road alligators you see along the highway were once under inflated tires. They didn't come apart because they had too much air.

Having one of your rear duals tear apart at highway speeds because you found it too difficult to check it, qualifies as a very interesting experience.

I give up. What is your tire after you have driven for the day.? I know at 115 lbs or 120 lbs my coach is all over the road.Is there something wrong with my coach?
lenny

Have you looked up the recommended tire pressure for your loads on each wheel?

You should not over pressure testing! Fill the tires, as has been said in many post here, to the recommended tire pressures in the AM when the tires are cold. In Florida I would not worry about a lb or two if the outside temperature is 50-60 degrees. After that DO NOT change your tire pressure after running, measure, sure, but DON"T change it. This is kinda like measuring your blood pressure, don't over do it.

If your coach is "all over the road" and you had started with the recommended tire pressure in the AM, then YES, there is something else that needs attention!

Just going to expand on ED a bit.

To get the proper inflation here are the steps.

1. Get you coach weighed by axle. By tire would be nice but not needed for this. Divid the axle weight by two for the weight front each tire is carrying and by four for the weight on each rear tire.

2. Find an inflation chart, preferred by the manufacture of your tire, but most manufactures are about the same. This will give you the correct cold pressure for each tire.

3. In the morning, before driving your coach, air to the correct pressure. Do NOT measure air pressure after driving all day!

As a side note I have found radial tires a little squirly if overinflated.

quote:

Originally posted by Gary Carter:
As a side note I have found radial tires a little squirly if overinflated.

This is especially true if you drove under inflated for awhile beforehand.

quote:

Originally posted by Gary Carter:


Get you coach weighed by axle. By tire would be nice but not needed for this.

If you have gone to the trouble of getting to a weigh place, it is very little more trouble to weigh each corner. A heavy genset on one side, for example, could make a significant difference. If one corner is heavier, all tires on that axle should be inflated to the pressure required by the more heavily-loaded wheel. The benefits of this will vary from coach to coach and from tire brand/type, but there can be a noticeable difference in handling, particularly up front.

quote:

Do NOT measure air pressure after driving all day!

My own practice is to measure either pressure or temp, but not to adjust unless one is lower or hotter than the others.

A tire billy is fairly good, too, but not as accurate. A trucking magazine did an article using experienced OTR drivers, and found that a palm temp feel was more accurate. My palm is not calibrated, but it can detect whether or not they are all the same. This was before temp guns were common.

OK got it . JUST thought that max.tire pressure was max even when hot.I have never changed tire after driving. One of my first few post was about tire and I said it was squrilly most every body said try to lower tire pressure and did it, it worked.They were to high 120 lbs cold that what north trail put in the tires. This is our one year bought feb 6th picked it up feb 20 kept it at 95 lbs since then . I am just leaving it alone .
thanks guys
Not bad in one year to get it running the way I want it was only $3600 parts and upkeep plus 7700 miles. Going to go to the trip book today and average mpg. let you know later.
thanks again lenny

Just when you think that the tire dealers are experts--the last time I had new Goodyears put on the Barth, I happily drove home with the new shoes, but noticed a vibration. Went to another Goodyear dealer and found out that two of the lug nuts were loose, the new dealer didn't have a torque wrench, and the original dealer had inflated all the tires to 120# even though Goodyear's reccomendation was 70#(in their own manual). Go figure. BTW, both dealers were truck tire 'specialists'.