I need someone with alignment experience to consult with regarding abnormal tire wear.

The vehicle is a '91 Aerostar, the E-4WD version. I obsessively maintain this vehicle, have owned it since new and has never been in an accident. Around 200,000 miles, both inner and outer front tires edges began rounding off earlier than in the past. Alignment specs revealed toe, caster, camber all well within range. Rebuilt entire front suspension, tie rods, ball joints upper/lower, new lower control arm bushings, shocks, sway bar link bushings. New tires and alignment done, no changes in alignment specs from the time prior rebuild.

Fast forward to first 5,000 mile rotation on new tires and installer notes inner edges on both fronts wearing rapidly. Back to alignment shop, toe slightly out, was re-set, camber/caster specs unchanged from previous times. At 10,000 mile rotate/balance installer again notes front inner edges wearing too quickly, now down to point of no tread pattern. Took van to a different alignment shop, same result, no alignment irregularities found.

Pulled the front wheels yesterday around 15,000 mile mark and noted to my horror, the right front inner tire is worn down so far the steel belts are exposed about one-fourth of the circumference and the inner lining is exposed on the remainder. The left front is still worn but not as severely as the right. These are Yokohama AVID Touring tires which I have used on three other family cars without problems.

I'm at wits end about this situation. Any thoughts at all, about what can cause such severe wear while the alignment specs remain within specified ranges?

 

I'm sure the tire presure is not too low according to the spec on the side wall, right? Is it full time awd? Is the front axle getting an uneven amount of power applied to it? I'm not too savy on that system, but if something is binding in the front drive it may cause abnormal wear. Or inner tie rod ends of the rack are worn causing irratic toe, could be why the alignment changed the second time? Not too sure just thought I would inspire some thought.

 

youngblue,
Thanks for the reply. Some inspired thoughts are definitely needed. I am in the process of replacing the upper control arm bushings. The rear bushing on the affected right was pretty soft and squishy but otherwise intact and no gross deflection of the control arm could be detected prior to removal. This is an E-4WD system with electronic lock-up as needed. One would think a condition causing such severe wear would stick out like a sore thumb during the alignment process.

 

Sounds cool, good luck, let us know what you find! I have an 2wd cargo aerostar w/lots of miles.

 

I bought a F250 that was showing a lot of wear on the inner edges. The problem was the ball joints.

I know you said you replaced them, but that's all I can thnik of.

 

Bumped for update:
Problem solved: While replacing the steering rack I decided to go ahead and change the upper ball joint bushings even though they appeared in good shape, had no detectable play by hand and all the previous alignment specs indicated the camber was well within the limits.

Once the vehicle was off the jackstands it was immediately evident the right front tire sat more upright than before. The steering effort is also much less than before. I am now positive the problem was excess camber from worn bushings despite what the alignment stats indicate.