I just got back from a 4,000 mile trip out west. My right front tire has about a 1/4 inch wide divet on the tread. It is about one inch from the outside edge of the tire. None of the other tires are showing this kind of wear. I am curious if air pressure is the main cause? I left with 90lbs of pressure down south and when I got to Amarillo, the air pressure was above 120lbs in that particular tire. The air pressure was much higher in every tire, but that one was higher than the rest.

Take your coach to a well equipped shop that has the equipment to check the thrust angle on your rig. I am sure that you will find that the rear end is not in perfect alignment with the center of the coach. If the rear axle is not aligned properly, the front end alignment is close to useless because the rear axle is always trying to push the front end sideways. Any shop that has the right equipment can do this. The other shops, that do not have the equipment, will tell you that the rear axle is not adjustable(they are wrong) and that all you need is a front end alignment. Thrust angle adjustment

You will need a larger than "Average" shop to do this kind of work. I had a really old shop - one that was established in 1953 work on my 97 Bounder. The front end of Ford chassis have axles that are "adjusted" by bolting them down to a large I-Beam, and using a 10 - 15 ton jack to change the angle of the axle, so that the tire starts standing straight up, and not leaning inward or outward. The factory specs say that it is 'not adjustable' and anything between 1* to the right or left is 'fine' and within tolerances. This is a very heavy duty front axle design, just like used on trucks way back in the 60's and 70's. It has proven very reliable, and once properly adjusted, your tires will last a really long time. My front tires got over 42,000 miles on them, before replacing them at 7 years old. Still had about 1/2 the tread left on them. I only had one alignment when the RV was new, and had it checked again at around 25,000 miles because I was having a problem with my car being towed behind the RV, ended up the RV alignment was still great, and not needing adjustments. Your tire pressure will increase with temperature. This is why they say to check it 'cold' or within say 5 miles of starting a drive. So if you check it at a campground and find it is 85 PSI, and should be 110 PSI, then drive 35 miles to a truck stop, measure it at 98 PSI, and only increase it to 110 PSI, you will find it has increased 13 PSI due to driving, and will only be in the 95-98 PSI range the next morning at another RV park.Also it will change with climate. Say you check it in Michigan and find it is 110 PSI at 40F. Driving might increase to around 120 - 125 PSI, then stopping in Texas RV park it might read 118 PSI in the morning when "Cold" at 75F. In this case, if it is 118 PSI at 75F, reducing pressure to 110 PSI cold at 75F is fine. But if you check the tire pressure at a rest area, after driving say 100 or 300 miles, expect the tire pressure to be 8-15 PSI higher than cold. It will increase more on a cold day, because colder air will expand a lot more than warm air.Good luck!Fred.

Yes you need a place that works on trucks not cars. What make are your tiers?Bill

mc.cc wrote:I just got back from a 4,000 mile trip out west. My right front tire has about a 1/4 inch wide divet on the tread. It is about one inch from the outside edge of the tire. None of the other tires are showing this kind of wear. I am curious if air pressure is the main cause? I left with 90lbs of pressure down south and when I got to Amarillo, the air pressure was above 120lbs in that particular tire. The air pressure was much higher in every tire, but that one was higher than the rest.Post a pic.Rivering is a design issue and often considered normal by the manufacturer.Cupping is usually a balance vs shocks issue. Get a lug centric balance for best results.

Some brand designs have more trouble with "rivering" than others. It is a design problem, and there is not much you can do, other than use a different tire next time. You just live with it, until time to replace tires.

Real cause of "rivering" or cupping? Air pressure?

22 Replies

CA_Traveler
Explorer III
Jan 03, 2015
In OR the scales remain on 24/7. Once I went through when they were open but first waited until there was no truck traffic. A few stations are also flat off to the side so I did a second pass and measured just one side. That gave me the needed individual location weight to calculate the axle pressure. But as Bikeboy57 said the total axle weight alone is a step forward in setting the correct pressure.

There is a old post about one camper moving his generator to the opposite side in order to get the side to side weight balanced. Shame on that rigs mfg.
tinkerer
Explorer
Jan 03, 2015
I just changed out my G670's and after 8 years and 38,000 miles they look just fine. I changed them because of age. I bought Handkooks because of price. Hankooks seem to get good reviews on this site, but I wonder if the reviews will be the same in about 5 years.:@
CA_Traveler
Explorer III
Jan 03, 2015
Good advice from Bikeboy57. If you are passing through a high elevation area then no need to adjust the tire pressure. The tires will handle the tire pressure just fine. How many millions of commercial vehicles never adjust tire pressure and they travel?

For extended stays at a significantly different elevation then adjust the air pressure.

OP Elevation changes don't explain that one tires higher pressure. Was it in the sun or otherwise warmer? Doesn't seem likely that the tire wear was the cause but???
Bikeboy57
Explorer
Jan 03, 2015
To the OP, a couple of points.

Your rise in tire pressure cannot be attributed to change in altitude. Here is why. Normal atmospheric pressure at sea level is 14.7 psi. Most guages measure in psig, meaning the 14.7 has been zeroed out. If you were to fill your tire at sea level, and then magically transport your RV to deep space, the ultimate high altitude, where there is no pressure, then the maximum increase in air pressure in the tire would be 14.7. The 30 lb increase you originally mentioned is not due to changes in altitude.

You have mentioned you added some air, then you said you adjusted it again. Please take your rig to a truck stop with scales and weigh the axles. Use those weights and the inflation tables to know the proper inflation on the tire. It is entirely possible that I misinterpreted your post on this. It could be that 90 is a perfectly fine pressure for your front tires. However, the placard in the coach, and the max inflation pressure on the tire are not good substitutes for know the actual weight on the tire. Purists will say to weigh each tire, and that is absolutely the best. But knowing the axle weight is far better than assuming a weight for the axle.
CA_Traveler
Explorer III
Jan 03, 2015
John Wayne wrote:
Are your tires GoodYear G670's? all my front GoodYears did that, no more problems after I went to Toyo's
X2 Except that the correct name is BadYear.

When I first encountered this wear at 6,000 miles BadYear had a picture showing the wear as a defect that had no warranty. This problem occurred on both the front and rear tires and is not a rig problem.

I dreaded buying our second DP which again had the BadYear G670 tires. And sure enough the rivering wear soon became apparent.

No more BadYear tires for us.
jerseyjim
Explorer
Jan 03, 2015
"Rivering" has been discussed many times here on the forum. Fron what I gather, this Goodyear rivering problem is partial to the 22.5 inch tires.
So far, never heard of it happening on a 19.5 inch Goodyear tire.

Personally, I've never had the problem. I have 19.5 inch tires (6 of them) and the motorhome came with the Goodyear G-670...and I've replaced them twice with the same model tire. Once because of milage (38,000) and the second time because of age (7 years).
moisheh
Explorer
Jan 03, 2015
Good Year G670= JUNK!!!

Moisheh
mc_cc
Explorer
Jan 03, 2015
JimM68 wrote:
"Rivering", that is, heavy wear in a single groove around a tire, isn't readily explainable, and is way different in appearance than cupping or scuffing or alignment or air pressure related wear.

This is exactly what is happening. "Rivering"
johnsonbert
Explorer
Jan 03, 2015
Here is a reference to tire wear issues and some of the causes. If you scroll down to Erosion wear, you will see a perfect example of rivering. clicky. We had an 01 Ambassador, G670 Good Years and Aligned by a good truck shop before tires installed and aligned again in 10k miles and both fronts looked like this at 15K.Rotated them to the back and figured I could get 3 rotations before replacement by age. Hope this may help, Happy Trails Bert
frankdamp
Explorer
Jan 03, 2015
Not having ever seen a definition of either rivering or cupping, I'm assuming the "rivering" is a wavy wear pattern across the traed and around it and that "cupping" is a deeper wear pattern across the width and at regular intervals around the circumference.

Based on engineering priciples and these assumptions, I would expect "rivering" to be caused by either a bent wheel rim or a loose wheel bearing which allows the wheel to wander in the yaw axis.

I would expect "cupping" to be either a function of wheel imbalance or a dented wheel that allows fluctuation in the vertical axis of the wheel.

Am I making incrorrect assumptions?