Are there any major mechanical disadvantages to having tires at max psi (80 psi) besides ride comfort? (2001 DRW) Any experiences?

Thanks for your replies

 

you would want them at max if you are loading/hauling at max. Some say to air down for some ride comfort if you are emtpy. Too much of a pain for me to air down then air up.

I just leave mine up. Remember take your reading with the tires cold.

 

Mechanical disadvantages?

Your tires may wear faster down the center.

Your braking distance may not be quite as short, but it might not be enough to notice.

I understand not wanting to adjust pressures up and down all the time. But on the other hand, most of us will rarely load up to maximum GWVR either, so there is room to reach a happy medium at somewhat less than the pressure on the safety label.

My safety label states 75 PSI. I run between 55 and 65 PSI depending on the season. Just giving that as an example.

On the third hand, running at max pressure will maximize your fuel economy.

 

Noticed the OP has a dually. Maximum pressure ratings on tires is often lower when used in dual mountings. Check the side wall on your tire to see if yours are rated like that. I think it has something to do with clearance between the tires, but I'm not entirely sure of the logic.

 

Max rear pressure stated on my door is 65 psi. Max pressure stated on each tire is 80 psi.

 

Actually, weight ratings are what's different in a dually setup. Each tire's weight rating is about 10% lower than the same tire in a single mount setup.

The reason is so that if one tire blows/fails, the other tire has some chance of keeping up the load for the few miles necessary to get to a tire shop.

-blaine

 

I believe the lower load rating for max psi on dual setups is to minimize the sidewall bulges at bottom of the tires from rubbing against each other and causing heat buildup.

 

spreading the weight accross more area I would think would allow a lower psi.

 

I am with senix on this. My E rated tires state 80 psi as max and since my GVW is consistently higher than 12K with trailers I run @75 psi most of the time. Rears go to 80 when I have the 5er hooked up with it's loaded kingpin weight of 6500lbs.

I could run at 65 but I like the feel of harder tires when I tow, which is a lot. The ride softens quite a bit when I am loaded.

When I had a dually I ran the same way except the wear pattern in the center of the tires was more of an issue than with my current SRW. Might want to watch for that.

By the way, we are all assuming you have E rated tires. If you have G tires I think your max is 90, D tires are down to 55, I think...

 

If I remember right most LRD tires are rated for 3195 lbs each at 80 PSI. Blaine is correct about lower weight ratings for duel setups, but I'm not sure of the exact number for our tires.

Anyway, if you're going to have significantly less than that weight on each tire, the pressure should be lower to maximize tire life and improve handling. Tires are designed for the entire tread surface to be in contact with the road at all times, not just when loaded.

At 80 PSI, you're inflating your rear tires to support an axle weight of around 12,000 lbs! They wouldn't wear properly and could cause handling issues.

Joel, you really put 6,000 lbs pin weight on your truck?

 

The truck I bought recently had tires which were kept at max (80 PSI) by the previous owner all the time when not under any load. The life of the tires were shortened by at least 20K due to being kept at max when empty. The center tread was almost completely gone while the other parts of the tire had significant tread left. Had to get new tires and I run them between 60 and 65 now.

 

Is that not over the weight rating of both the tires and axle?

You should have 6,800 of tire cap. and 7,500 of axle cap.

 

That's why all of us should to the chalk test for our normal loads....

Each truck and tire combo 'could' have a better sweet spot psi ....

loaded and unloaded will call for different psi's... but at least get a happy medium so that type of thing doesn't happen....

fyi - Pocket had a good writeup about the chalk test a while back :

Every tire brand/model is different.
Once you switch tires from the originals, the door sticker no longer matters.
In fact, the door sticker doesn't even matter with the originals.

Towing and running empty are two completely different animals. Too much tire pressure when empty will cause your tires to wear faster. Too little pressure when loaded down will cause excessive sidewall flex and heat, leading to faster tire wear.

If you want to know proper tire pressure, do a chalk line test. This test is simple, just draw a chalk line straight across the tire tread. Drive a few tire revolutions (no turning!), then check the chalk line. If the chalk is worn off the middle but not the sides of the tread, you are over-inflated. If the middle is unchanged but the sides wore off, then it's under inflated. If the chalk line wears off evenly, then your tire pressure is perfect.

Do this test while empty to find the proper unloaded pressure,
then do it again with your trailer hooked up to find a proper loaded pressure.

(And front and back may be different too )

 

I set mine at 65 PSI. Setting at Max tire pressure means wear patter is concentrated at center! not good.

 

It's been a while but yeah, my 250 4X4 is rated for either 6300 or 6500K on the rear axle and I hit the factory limit when my 5er is loaded, it's an enclosed cargo trailer. If I remember right, my front axle was around 5400, rear around 6000 and the trailer was around 11000. It has triple 7K axles and G rated tires.

This is also why I have the airbags. Without the bags the rear of my truck drops about 4 in. Not too bad but enough to make me feel like I am going uphill all the time. Believe it or not, this 5er tows better than any other trailer I have used. I really do forget it's there, virtually no stability issues of any kind.

I didn't mean to attract so much attention here! Hope none of you are DOT folks......