Weird Tire Wear

[SentraWV]

I know heavy front drive cars are supposed to eat front tires (soft autoX tires all the moreso), but what about the rears?

With the championship in SCR wrapped up, I decided to get the Dunlops unmounted in favor of some more streetable tires. The Dunlops are in good shape and will work next season, except for the one on the right rear - it's just about bald right down the middle of the tread. The other three tires are fine - normally worn, but fine.

Any thoughts on what would explain the right rear wear?

[gtfour77]

Jon, Have you checked your alignment lately? Frequent autocrossing can quite easily slip the alignemnt out of spec. On the celica I had to remove the rear strut housing and scuff down the spindle mating surface in order to stop camber slip.... Also, wear in the middle of the tire would indocate high tire pressure, but I am sure you check yours quite often especially during autocrosses. Do you deflate your tires after each autocross? I know these are very basic questions but thought I'd ask before we start digging deeper...

[johnnytavo]

if your alignment is good, is there a warranty?

[ShortysTRM]

I'd say it's either a bad tire or it was just way overinflated, but I have a feeling you wouldn't run on them without leveling pressures. All other factors aside, it really sounds like there may have been a problem with the tire itself. Just my guess, though.

[SentraWV]

I don't think it was a pressure issue, unless something in the tire itself was causing it. I always bleed at the end of events and the rears don't really change all that much from road pressures to begin with.

The alignment theory makes more sense. I had not had one since the Dunlops were mounted (until yesterday, of course) and the car had developed an annoying minor vibration that went away with fresh rubber. I also know that Mazda recommends some sort of camber kit with its coilover setups to keep the rear end aligned.

NP: Adrian Belew, "Hot Zoo"

[gtfour77]

Wear on tires will cause vibrations...just make sure you check your tires every oh.. 1000miles or so, run your hand through the tread and see if you have any chopping or feathering which would indicate either a bad alignment, shocks or even defective tire... Glad to hear everything is good with the new rubber.

[SentraWV]

An update.

I stopped at Brit on my way home today and had them bolt on my snow tires (yeah, I'm lazy http://www.iobloggo.com/static/img/smiley/deviant/icon_sleep.gif) and go an alignment. The alignment specs were all out of whack, after only one autocross. So I think that might explain things.

Any thoughts on how to keep the alignment specs tight from event to event?

[gtfour77]

An update.

I stopped at Brit on my way home today and had them bolt on my snow tires (yeah, I'm lazy http://www.iobloggo.com/static/img/smiley/deviant/icon_sleep.gif) and go an alignment. The alignment specs were all out of whack, after only one autocross. So I think that might explain things.

Any thoughts on how to keep the alignment specs tight from event to event?
The only thing you can do Jon is to check your alignment frequently. You (any autocrosser) should scuff the surface of the strut to spindle mating surface to give it a little extra grip. Tighten the bolts and nuts really well. If you have good scuffed surface( use 40 grit sandpaper) without anything between the two parts (paint, oil, grease, rust) you should not have any problems. Many cars utilizing the traditional mcpherson strut will have this issue especially with accentric bolts.

[Jason V]

I used to use paint pens to mark alignment settings so I could see visualy if they moved.. Also, I marked tie rods and ends to count turns for making toe changes at events... I have an idea for a simple toe fixture for the Kart... (castor and camber adjust with "pills" for the king pin Bolt so that is easy to keep track of....!!