27 replies to this topic

[Whoachubby]

I have a 36 foot Discovery and noticed that the front tires are cupped on the outside of each tire.

A little research on the net and it seems that this condition suggests that the camber is out of adjustment. Where is the best place for alignment ? A regular Firestone type store or a truck dealer. Ideally it would be somewhere that I could buy new tires if need be.

By the way I just put the steer safe brackets on the coach prior to a 500 mile trip. I noticed the tires after the trip and hadn't really noticed the cupping before. could the steer safe have affected the tire wear?

[wolfe10]

Front-end alignment out of camber is very unusual on a solid front axle (assuming that is what you have) and rarely causes cupping.

And you may be looking for two DIFFERENT stores -- a tire dealer who works with OTR trucks and diesel pushers and a front end alignment shop who does the same. Yes, there are some who do both.

But, you will need to let us know what area of the country you are in so we may be able to recommend specific shops.

[Whoachubby]

The edge of the front tires are smooth with dips all around.

It is a solid axle . Any idea what would cause this type of wear.
All other parts of tires are great.

[Whoachubby]

The motorhome is currently In south Louisiana.

[hermanmullins]

Well no wonder. Alligators tend to do that to tires.
Brett is correct, You would have to have had a very hard hit to your front end to create a camber problem. If your solid axle camber was the cause, your tires would be worn evenly all the way around your tire. Camber would cause the wheel to be leaning either in or out. Leaning in at the top would cause the tire to wear on the inside and out at the top would cause the tire to wear on the outside of the tread.
Cupping would come from Balance or shocks. If all of your tires are the same age, have them rotated and have them all, front and rear, balances. By putting tires from the rear you can then tell if you still have cupping.

[rhuffhines]

On tires and alignment I have had good results using Purcell Tires and Service located in Austin, Tx. They are a national firm so there is probably someplace near you.

Also ask a truck stop in your area where the big trucks get that kind of service.

[Whoachubby]

I will check the shocks. since the coach is ten years old it would not hurt to replace. Is there a recommended brand ? I want the best available.

If I could get by with a balance and rotation that would be even better.

Thanks, for the help.

[hermanmullins]

Whoacbuddy,
If your coach is 10 years old and you have been pleased with the ride so far. I would consider staying with the brand that came with the coach. There are some very good shocks out there and you need to decide which ones suit you. I say this so in the future when you are complaining " " about the ride you wont say "Well Herman Recommened these shocks".
Good luck and smoother riding.

[Tireman9]

While I can't offer advice on where to get the work done I would suggest you call first as many tire stores and alignment shops are not equipped to handle what is essentially a heavy truck front end alignment.
You mentioned Firestone tire store. Many can not handle heavy trucks but you might check their web site for store locations near the RV location.

That link also has an "Ask the tire Doctor" link and I found this reply concerning right front tire shoulder wear after front end parts change.
" If examination of the left-front tire shows no side force wear then a likely culprit would be a positive camber angle on the right-front.
a. Was the steering axle replaced as part of the repair?
b. Did the alignment shop give you a print out of the alignment specs, as received readings, and after- alignment readings?
c. If you do have such a print out, make sure the right-front CAMBER angle is either 0 or slightly negative. Any positive setting will lean the top of the tire out and wear the outer shoulder on the tire.
d. If the right-front does have a positive camber angle, the axle should be replaced (do not bend the axle as this voids any warranty)."

There is also a post on a similar type of shoulder wear
"From the description of the irregular wear that you give, its sounds like you are describing what the Technology & Maintenance Council defines as Cupping/Scallop (Shoulder Wavy) Wear.
TMC describes the appearance as: "Localized cupped-out areas of fast wear creating a scalloped appearance around tire on the shoulder ribs. May progress to adjoining ribs." TMC gives the 'Probable Cause" as: "Usually a result of moderate to severe assembly out of balance condition, improper rim/wheel mounting or other assembly non-uniformity. Can also be due to lack of shock absorber control on some suspension types as well as loose kingpins and improper bearing adjustment. Underinflation can also cause this condition."

Here is a link with pictures and probable causes of various types of irregular wear on tires.

[Whoachubby]

What great information.

I haven't had the coach that long but since I started reading the forum and saw the importance of tire pressure I checked the tires and they were around 55 pounds. Increased pressure to 90 for my trip and the next day it was 28 degrees . Tire pressure went to 80. Stopped and reinflated to 90 for the ride home.
540 miles.

A few hundred miles into trip air in tires was heating up and pressure went to 95.

Based on your reply it may be the under inflation is a factor.

Thanks

[wolfe10]

If, repeat if the recommended tire pressure for your actual weight is 85-90 PSI an the tires were run any distance at 55 PSI, that qualifies as RUN FLAT by tire manufacturers and they should be replaced. The flexing that occurs with tires that underinflated can severely damage their structural integrity.

[Whoachubby]

Ok , I see the point and Iam very glad I have joined in the information on these forums.

Now that I am educated and have a possible hazardous situation on my hands can I dismount the tires and verify the integrity before I replace 3 or 4 thousand worth of tires?

[hermanmullins]

Whoachubby,
You are most likely running 6 each 275/70R-22.5 tires or there abouts. You did not say what year coach you have. If your coach has the original tires and your coach is over 6 years old, you are in need of replacing your tires. 6 to 7 years is max for RV Tires. They may look good with deep tread but looks can be deceiving. I just replaced the tires on my coach and boy did they look good. No crazing on the side walls with wonderful tread, but when they were taken off the rims and were leaning against the wall I look down between the treads. There were crack and crazing all the way around all of the tires.
If that size tire were to have a blow out, you can have damage far beyond the cost of the tire. One friend-one blow out= $7,000.00 damage to his coach and two months in the shop.

BE SAFE, check out the dates.

[wolfe10]

As a follow up, on one sidewall of each tire is a complete DOT number. The last four digits (usually in a slightly different-looking area, as this part of the mold is changed each week) are the WEEK and YEAR the tire was produced.

Note, the complete DOT number could be facing inboard, instead of being on the outside where it is easily read.

Brett

[hermanmullins]

As a follow up, on one sidewall of each tire is a complete DOT number. The last four digits (usually in a slightly different-looking area, as this part of the mold is changed each week) are the WEEK and YEAR the tire was produced.

Note, the complete DOT number could be facing inboard, instead of being on the outside where it is easily read.

Brett

Don't you just hate that.

[Whoachubby]

Ok
I had to crawl under coach to find dot # .
Looks like it is 2102 so it make them 10 years old.
Will the fact that the coach as been parked inside for that time period have any effect ?

I am trying to justify not buying new tires but would rather err on the side of safety.

[wolfe10]

NO.

Even under ideal conditions (always properly inflated, always protected from UV light, no road hazards, etc) 10 years-- the "Fat Lady Has Sung".

Don't risk your and your family's life.

[Whoachubby]

Well I'm on it .

Now the search for tire deals.

Thanks to all for the follow up info on this thread.

I have a lot of precious cargo ( grand kids) when we travel and I can see that the tires are the most important safety feature on the vehicle.

Had no idea of the potential hazards since the tires look so good.

[hermanmullins]

Michlin has a program through FMCA. If you look at Goodyear G 607s ask you dealer about their rebate per tire. When I bought my G670s the dealer got me a $50.00 per tire rebate.

One thing I have found since I became this old person is that alot of Senior & Veteran, gets you a discount. Its "Don't ask, don't tell", if you don't ask they wont tell you about any discounts.

Good luck on your new tires.

[2BuckeyeHams]

Would anyone hazard a recommendation or two on where to get Michelin Tires through the FMCA Advantage National Account Program. The tires (255/80R22.5G)are due for replacement (DOT 1205 and some sidewall cracking); especially if we go w/ our plans to drive to Labrador/New Foundland this summer. We are in central FL and are looking for somewhere from Sebring north (last week of March). I found a couple of dealers on the Michelin RV Tires web site that do "national accounts" which I believe is a prerequisite; TCI (Mulberry, FL) and Dan Callaghan Ent. (Lakeland, FL). Both appear to have several locations in the SE or the U.S.

We will also need an alignment and shocks (the coach is doing a bow at each red light). Should I get these also at the tire dealers or separately (e.g. the shocks? Suggestions for make and sources of shocks for our coach (see below) are welcomed.

TNX - Nelson