Strange Tire Wear

RJ · December 30, 2017, 07:52:50 PM

All -

Here is a strange: We tow a 2003 VW TDI 5-spd Jetta Sportwagen that we've had for a number of years. The maintenance has always been kept up, including wheel alignments and tires rotated at 5,000 mile intervals.

Over the last 18 months we've put 16,000 miles on the RV, 90% of the time towing the VW. I noticed today while washing the car that there's a definite wear pattern developing on the front wheels to indicate a "toe-out" situation, i.e. smooth inside edge to the tires.

So I ran the car down to the local tire shop that has an alignment rack, where they checked and the alignment it completely within specifications! Huh? Why a "toe-out" wear pattern if the alignment is within the manufacture's specifications?

Thus, I'm wondering if there's a change in the front toe between being "under power and driven" as opposed to simply "rolling along" while being towed. Totally stumped...

Oonrahnjay · December 30, 2017, 08:01:28 PM

Quote from: RJ on December 30, 2017, 07:52:50 PM... Thus, I'm wondering if there's a change in the front toe between being "under power and driven" as opposed to simply "rolling along" while being towed. Totally stumped...

Yes. Range Rovers from the mid-90s showed that issue. You had to set toe-out for them to run straight under power. I'm not sure that it's enough of an effect to make tire wear problems when towing the vehicle -- but 15,000 miles is a lot of distance. I run Michelin Energie tires on my 03 TDI wagon and I don't expect to get more than 75 -80,000 miles out of them, so that's about 1/5 or so of the entire life of the tire. Maybe this is exactly the issue you're seeing and not many people see this because they don't tow those mileages on FWD or AWD vehicles.

chessie4905 · December 31, 2017, 03:56:58 AM

There is a difference between meeting specifications and being right on. Called acceptable or desired. Is the rear right on? Sometimes an unusual wear pattern doesn't show up or isn't noticeable without measuring until there is significant overall wear to tread. Maybe camber is off enough to do it. Some fwd or awd cars are not adjustable except for toe in.

luvrbus · December 31, 2017, 05:14:47 AM

It sounds normal for a towed vehicle they drag a lot since the power steering is not working and it takes longer to react to turns ,small bobbles and sways in the roads

gumpy · December 31, 2017, 05:19:34 AM

Have the tires flipped on the rims. Move the wear to the outside edge. Keep rotating properly.

luvrbus · December 31, 2017, 05:42:00 AM

Quote from: gumpy on December 31, 2017, 05:19:34 AM
Have the tires flipped on the rims. Move the wear to the outside edge. Keep rotating properly.

Yep and watch the front tires they are going to lose the tread over time and make a mess

Geoff · December 31, 2017, 08:28:47 AM

Tire wear on the inside is probably from loading the inside of the car past it's normal capacity and throwing off the camber. I've had that happen with my pickup.

chessie4905 · December 31, 2017, 11:54:17 AM

A general run of the mill alignment shop doesn't get much concern over caster or camber if it is fixed, just saying it's in range. A good shop will give specs,vs. ideal. They make items to deal with these issues when they come across them. I doubt a Firestone or Monroe alignment shop would fool with them.They just set to in and done.

kyle4501 · December 31, 2017, 01:43:32 PM

I finally found an alignment shop that will listen to my descriptions of how my car was handling.

They set my suburban 'out of spec' in order for it to track correctly & not scuff the tires AND to not go l'loose' when towing a trailer. Got 8 years & almost 65k miles out of those Michellins. Never bothered to rotate them since the tread wear was so even.

A good alignment shop should be able to set your alignment properly after listening to your description of use & looking at your tires - they may find something worn too . . . .

Geoff · December 31, 2017, 02:10:14 PM

Something that should be mentioned is that a towed car/pickup does not get mis-aligned by being towed. RJ says his toad front tires are wearing on the inside. That is negative camber. It can happen from weakened springs or additional weight in the vehicle. It could be adjusted, but if it's due to weight, he'll have positive camber when he unloads it to drive around.

kyle4501 · December 31, 2017, 06:03:35 PM

Excessive toe-out will eat up the inside of the tires too.

Sometimes, a worn part will allow things to look perfect on the alignment machine, but allow the alignment to change drastically when at highway speeds.

Caster, camber & toe all affect each other. Sometimes the tires need to be preloaded to simulate the effects of the road.

If the front wheels are pulling, the suspension clearances are pulled by the tires - When the front wheels are being pulled, those clearances are pushed.

Someone who understands alignment & the suspension can adjust it for the best compromise to minimize tire wear & still maintain good handling & road feel.

Something else - I saw a motorhome that when he was stopping, the back of the coach raised up allowing the towbar to rise in the front - effectively pushing down on the toad as the toad pushed the coach. Depending on the effectiveness of the toad brakes, there could be significant downforce. . . . .

Jim Eh. · January 01, 2018, 12:14:01 AM

Your Jetta, being front wheel drive has a spec with toe out due to it being the driving axle. As power is applied it tends to the wheels inward (back to zero toe) while in motion under power. Now you remove that "power" and the toe out is only compounded by being dragged along the roadway.
If the car does more getting towed than driving then have your alignment shop set the toe in a little closer to zero.
Sadly no "golden rule". You will have to experiment or ask others with the same car (with the same engine option) if they are successful in modifying their toe setting to achieve good toe wear.

bevans6 · January 01, 2018, 04:59:03 AM

I think it's just down to the car being towed vs the car being driven. When the car is driven the front tires transmit the power and guide the car. When you turn the wheel, the cars inertia tries to make it go straight and the tires force it to turn, with more load on the outside front tire. The car pushes the tire and wear is organized towards the outside of the tire, and alignment compensates for this. When the car is towed, the tires are forced to try to run straight by castor. When the car turns to follow the bus, the road forces the front tire to turn, against the natural force of castor and against the stiffness of the inactive power steering, and the forces on the tire tread are the opposite of normal driving, so the tire wear is organized towards the inside of the tire from being scrubbed across the road surface. I doubt there is anything that can be done to mitigate this completely.

Brian

luvrbus · January 01, 2018, 05:51:18 AM

I towed Jeeps for over 20 years and never owned one that didn't show inside tire wear at about 10 to 15k miles except the 1 with 31" tires it would show inside tire wear at about 8k miles and I could never stop it from wearing when I towed it 4 down lol and the Mickey Thomson tires were not cheap.
A alignment center in Eugene Or told me to over inflate the tires by 5 lbs and it would help but I never tried it so I don't know if it works or not

chessie4905 · January 01, 2018, 06:22:36 AM

After rereading his first post, I don't know if he has towed this car for years for many miles and never had a problem or first tow, or first tow putting on that many miles. If latter, reverse tires on rims so wear is on opposite side. Make sure camber is right on, not in range, and what is his exact toe in. It could be tweaked some to compensate. If his 16k tow job is a one off, then maybe not anything to worry about. Just switch tires. Radials never seem to even out the wear patterns once they are there. Rotation would help if towing a lot. Does he have a tread depth gage? How much wear?