Toad tires wear

[Bill Lampkin]

My tire man just called to say the rear tires on the toad need replacing, as they are wearing on the outside edge. He suspects the wear is caused by being towed behind the motorhome. We tow with a Roadmaster Sterling hitch setup with a drop hitch on the MH so it tows level. Anyone heard of a flat tow causing uneven tire wear? Tires were new in 2016, we don't put that many miles on each summer (3k?). Toad is a Jeep Liberty. I don't think the rear can be aligned.

[Richard Davis]

It seems strange that it is the rear tires that are scuffed and worn.  I have towed many vehicles 4-down over many miles for the last 30 years.  There is additional wear caused by the side force and scuffing of turning the steering wheel and gear system from the tire rather than from the steering wheel as is normal.  But, that additional wear is on the front tires and not on the rear.  Is it possible the tires have been rotated from the front to the rear and the additional wear took place while they were on the front?  If the wear was truly caused while the tires were on the rear of the vehicle, I would suspect suspension component problems or inflation deficiency.

Richard 

[Bill Lampkin]

rear tires new in 2016, never had them rotated. New tires in front in 2018. I keep a close eye on inflation, as the Jeep has factory TPMS. As far as rotating tires to even the wear, that seems to say you accept abnormal tire wear and rotate tires so that all get a turn at abnormal wear. That seems abnormal to me, as I would like to know what is causing the tire wear in the first place. I had the alignment done at Kaiser wheel and Brake in Eugene Or in 2018. If I remember, the alignment sheet said the rear cannot be adjusted for alignment. I just didn't expect uneven wear, due to towing 4 down or from whatever cause. And my wallet didn't expect it either!

[Steve Huber Co-Admin]

Good practice is to keep track of total miles on toad tires and rotate them accordingly.
Steve

[Richard Davis]

Bill

What you are describing is definitely not a normal result of towing 4-down.  The only way both rear tires can be excessively worn on the outside shoulders is by having some force pushing the vehicle to one side and then the other while it is being towed (low pressure would cause them to be worn on both shoulders).  You might carefully observe the Jeep while it is being towed to see if it is fish-tailing back and forth while it is being towed (this might be a caster problem on the front suspension).  I do not see how this could be an alignment issue on the rear (since, as you say, the rear is not adjustable).  Anyway, this is certainly not normal and you need to continue to dig into the situation, otherwise you will just keep scuffing off tires.

Richard

[Bill Lampkin]

Thanks Richard! Tomorrow the tire shop will check the rear alignment. Jeep tows smooth, I have about 30k on the tires, maybe 12k towing, as we sit here at the S&B 'till summer rolls around. We'll see tomorrow.

[Eric Maclean]

Hi Bill
Wear on the outside of the tire is indicative of too much positive camber.
Regardless of whether the rear are adjustable or not an alignment machine should give you the actual readings for reference.
On a straight axle these readings should be somewhere near 0 degrees.
Any good alignment machine will read both front and rear wheels to determine the rear thrust angle for steering wheel centering.

On any vehicle tires are rotated periodically to avoid uneven wear the recommendation will be in the vehicle manual.
Four wheel drive vehicle's require more frequent tire rotation.
The wear carracterists of most tires are such that if they aren't rotated they will develop abnormal wear patterns .
This abnormal wear will normally show up as scalloping in the outter tread area and will create tire noise as well.
Unfortunately once the irregular wear patterns are started they are all but impossible to correct leaving little choose but to replace the tire.
There are may types of wear which can and will develop on a vehicle even if the alignment is correct .
Some tire tread patterns are more susceptible to uneven wear than others and there are even more variables at play as well
Things like vehicle loading.

The truth is that with a flat tow bar angle there will little to no effect on the rear tires if there would be any adverse effect to the alignment if would be more likely a front tire wear issue caused by the extra weight added by the tow bar and base plate.
On a Jeep I'd be surprised if the weight of the tow bar and base plate would have any effect.
It is possible the extra weight could cause a ride height change and inturn the alignment.
An old alignment man's trick is to align the vehicle as the vehicle will be driven ( IE if the owner is a salesman who carries heavy cataloges in the trunk to get a good alignment that weight should be in the trunk when alignment is performed.)
Using this theory the vehicle would be aligned with the tow bar and base plate installed and any added weight that is usually kept in the back of the vehicle.
The problem with this idea is if the vehicle is driving more than towed then the set-up would possibly create more problems than it solved.
As stated earlier tire rotation is the most over looked tire wear contributer and for some reason it is even more important on 4 wheel drive vehicle's.
Sorry for the long winded reply
Hope some of this helps
Eric

[Bill Lampkin]

Thanks Eric! Long winded; more info, I might even learn something. The tire shop says that the wear is only on the outer 1/4" or so of the tire. Plenty of tread depth on the rest of the tire. I have to replace both as one has a slow leak from a small nail thru the sidewall, not repairable. Will learn more, hopefully, tomorrow.

[Eric Maclean]

Bill it would seem that a 1/4 inch would be a very small wear area and not likely of much consequence.
Interesting that sounds more like a side scuff type of wear as mentioned earlier in this tread.
Eric

[Bryan Beamon]

Bill we have used a product from Road Master called Quiet Hitch for both our tow bar and the receiver drop. It eliminates any movement on the drop adapter and tow bar. It solved our front tire ware problem. Probably not your issue but others might benefit.

[David T. Richelderfer]

I do not see how only a 1/4" wide band on the outside tread surface of both rear tires could be caused by road wear.  It seems to be more likely the wear is from something in the wheel-well of the vehicle rubbing on the tires.  Perhaps the tires are the wrong size (meaning tread width and/or sidewall height) for the vehicle.  Just a thought...

[Bill Lampkin]

Agree 1/4" wear is not really an issue, I'm just interested in finding out what may be the cause. And I have the Quiet Hitch on both the tow bar and bike rack (on the back of the toad) when towing. Takes out all the slop in the hitch. Picked up the car yesterday late, but of course the 'service advisor' that took my payment is not the shop owner who, like me, wanted to know what caused the wear. So the story goes on.

[Richard Davis]

Bill

I noticed your comment about the bike rack on the back of your Jeep.  Have you considered the impact the weight of the bikes have on the Jeep while traveling.  The extra weight of the bikes swinging back and forth may be the cause of the side forces that are wearing the tires on the outside.  Just a thought.  Sometimes we don't think about the little things we add to our traveling homes as they go down the highway.  Also, we need to remember that Jeeps are taller and boxier vehicles that tend to be pushed harder by side wind forces.

Richard 

[Bill Lampkin]

I use a Kuat bike rack and Roadmaster Quiet Hitch. Nothing shakes at all using that set up. And I take the bike rack off when we're not travelling. I'll talk with the tire shop owner about the alignment on Monday. The tech reported the rear was in spec, although its not adjustable.