fuel economy costing me tires????

Hey all, havent been on here for a minute... 60 hour work weeks and busy weekends have kept me away from the habit

Anyway, just put my car in for service, and found my two rear tires were completely bald on the inside edge. Ive been running all my tires at 42psi, front tires were fine. Since i had no spare, and the tires were from the PO and were bo-bo brand, i replaced all five tires with new units and had an alignment done. everything seems to line up.

So the question is, does the solid rear axle on the 2000 jetta have built in camber that might cause higher tire pressure to wear only the inside edge of the tire? should i drop my rear tire pressure when im not on the highway? As it is, I plan on rotating my tires every 5000 miles, (every oil change, i run B20), tires are expensive. but wanted to pick yalls brain and see if maybe anyone else had this problem.

even with a lower tire pressure you'd still get that wear pattern if your alignment is off. it wasn't clear, but when you had an alignment done, was it in spec or was it off?

Apparently, a crappy set of tires will wear like that no matter what you do.

Going FORWARD, (at this point a best swag on incomplete information can be given... not much point...??) since your "new tires and alignment" are now the base lines.

1. Go back to the oem recommended rotations @ 10,000 miles intervals.

(very off topic: go back to the 10,000 miles OCI's)

2. While 42 psi is a tad sotp's and jaw rattling for me and the horrid freeways out here, (might be glass smoooth for you) I would drop the psi in the front to 85% of max side wall pressure (38 psi) and minus - 2 #'s in the rear (36 psi) and adjust up or down to suit. UNLESS you HAVE to carry a FULL load all the time. Check your oem owners manual for a full load psi, but mine (03 TDI) is 41 psi.

2b. Or if you are ok with 42 psi front, drop the rears by 2 psi increments or @ 40 psi/38 psi.

3.. Since you only have/use 4 tires AND if you do not have directional tires, go to a 4 tire CROSS rotation. (4 tires: fronts to rear, cross rears to front) (front to rear and rear to front are recommended by VW (same side) By way of explanation: all the tires hit ALL the positions at some time during the tires life, this tends to even out the tire wear. Again by way of explanation: tire wear from greatest to least is: 1. right front passenger 2. front left drivers 3. right rear passenger 4. left rear passenger. (I hope you can visualize, you will be putting the least wear rears to the most wear fronts?)

I did all 3 items (03 TDI) and got 112,300 miles on a decidely 3rd rate oem tire (GY LS-H) Tread wear was almost literally dead even across the tread.

Thanks all, sorry for the incomplete info, im at work and trying to spit out information without getting slapped in the back of the head

The main question was if high tire pressure had contributed to this on anyone elses car, answer seems to be no.

On my particular car, the tech did indicate the front camber was a bit off, but the right rear camber is off, my best guess is from an impact. Its only a bit off, i dont have the numbers here in front of me. But seeing as the spare tire was non existant, and the rim in the trunk was bent, its a safe guess that there was a rather substantial impact back there. At this point all specs are in the green except that right rear camber.

And the only way to fix that ive been told is to replace the rear axle.... id like to avoid that if possible.

So i think ill just stay on top of my tire rotations, and run slightly lower tire pressure around town. Thanks for the replys guys and gals.

ruking said:

.. I would drop the psi in the front to 85% of max side wall pressure (38 psi) and ....

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Not all tyres of the same size have the same maximum pressure rating.

Tires do weird things. With high inflation pressure, the tire may crown its tread so outside and inside edges actually lift off the pavement. So this area sort of scuffs along the pavement while the center of the tread takes the weight.

I know this happened on my Jetta when I put alot of air in the tires. Drove into my shop with wet tires and noticed that the whole tread was not making contact. So i reduced pressure til contact patch was complete. About 32 psi rear, 40 in the front (front always contacted fully, 40 is as high as I would go anyhow).

Different tires do different stupid things on different cars with different air pressures. But rotating really seems to work. I do it once per 10kmiles when I do oil change.

The tires that gave me the most trouble were the ones where I was slacker boy and skipped rotating.

Joe_Meehan said:

Not all tyres of the same size have the same maximum pressure rating.

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And correct you are there, Joe. For our cars Mk IV's, Michelin (there are a few others) specifies the oem H rated MVX4's @ 51 psi, I believe Conti's are 44 and certainly the GYLS-H's are. So the recommendtion is still the same, 85% of the max side wall pressure 44/51 psi. aka 38/44 psi., with of course the Minus- 2 psi to help to maintain the understeer bias (front end plowing, instead of the rear end breaking away suddenly) that was designed into our cars. Most folks know to get out of trouble (oversteer trouble within parameters of course) is to ease up on the throttle to let the end come around without sliding to the left or right.

grizzlydiesel said:

Thanks all, sorry for the incomplete info, im at work and trying to spit out information without getting slapped in the back of the head

The main question was if high tire pressure had contributed to this on anyone elses car, answer seems to be no.

On my particular car, the tech did indicate the front camber was a bit off, but the right rear camber is off, my best guess is from an impact. Its only a bit off, i dont have the numbers here in front of me. But seeing as the spare tire was non existant, and the rim in the trunk was bent, its a safe guess that there was a rather substantial impact back there. At this point all specs are in the green except that right rear camber.

And the only way to fix that ive been told is to replace the rear axle.... id like to avoid that if possible.

So i think ill just stay on top of my tire rotations, and run slightly lower tire pressure around town. Thanks for the replys guys and gals.

Click to expand...

Well for sure a dinged spare rim and zippo to ruined tire might... be a clue... Obviously the best is get the tracking on the rear right end fixed, as cummulatively the right rear will wear ever so faster than "normal". So yes you are correct that higher TP is actually better than lower tire pressure. So for example while some would say that running 85% of 44 psi max side wall tire pressure and getting 112,300 miles is a damned fluke. No one who has run 26 psi T/P (on GY LS-H) on ANY oem tire has stepped up and said I got 112,300 miles (or close or app) on 26 psi. Indeed the majority who have run oem tire pressure report these tires as being toast between 30,000 and 50,000 miles MAX. This also might be a ...clue.

Rear camber change from an impact has only 2 possible cures: 1) shims or 2) replacement of the rear axle.

over inflation would wear the centers, your alignment or crappy tires are to fault.