Spyder_Man

Hey folks,

Over the weekend I discovered that my front tires have been wearing rather unevenly on the inside. I'm running Bridgestone S04s on 17" CUP 2 wheels with 225 front tread width and standard rear tread width. After about 8k miles here is what the fronts look like!


Note the steel poking through.

Both the left and right side have comparable wear. I've already got a replacement set of front tires on order and I'm taking the car into the shop today to get them tires replaced ASAP. Clearly there is plenty of tread left on the outside edges, but the insides are worn dangerously low.

I use my 993 for a combination of daily driving and backroad canyon carving. Currently the suspension is lowered to about RS+10 height, and overall I've been extremely happy with its handling. I don't have my exact alignment specs from when I had the car aligned, but I tried to emulate another RLers RS+10 setup.

Now based on my Boxster experience, I was expecting the REAR tires to wear faster than the fronts by a 1.5:1 to 2:1 ratio. Both my front and rear tires were installed at the same time and my rear tires look fine with probably half of their tread life left. I'm quite shocked to see my front tires spent at 8k of use.

Is this typical or exceptional tread life for those who have run Bridgestone S04s?

What am I doing wrong here (aside from driving the car like I stole it when on backroads)?

Should I start by easing off the front wheel camber?

Should I just watch my tire pressure more religiously? (I've been aiming for 32/36 PSI cold)

Is the fact that I'm running slightly wider front tread width tires (225 vs. 205) exacerbating the tread wear issue?

Thanks for your thoughts!

JB 911

Based on this statement, I would be cautious to adjust the camber! I am curious what front and rear camber are set at though if you can dig it up.

Vandit

Your toe is likely jacked up. Set toe and cross-toe close to zero.

A little toe-in helps with stabilty and a little toe-out helps with wicked awesome turn-in, but both will accelerate tire wear.

You're also probably running too much negative camber given your typical driving and driving style. You can run negative camber and still get even tire wear if you're the type of driver who is always ripping around corners (body roll spreads the wear to the outside of the tire). But if you're just doing highway miles and gingerly cornering, then your negative camber will likely wear the inside faster than the rest of the tire.

Regardless, aggressive toe will kill tires much faster than aggressive camber.

And yea, what JB said. An alignment that feels good might not be the most friendly to the tires. It's all a compromise.

Vandit

Also, what's the status of your front control arm bushings? If they're failed or getting there, then geometry will be all over the place.

A good alignment shop should check that before they proceed with aligning your car.

Spyder_Man

I've asked the shop to give me the current alignment specs before diving into realigning. I'll ask them to give a close look at the toe adjustment.

Also regarding bushings, they have all been recently replaced in the last couple years, and where applicable elephant sport bushings are being used.

Lastly, I get that great handling and great tread life run counter to each other. While Id like to be spending 90% of my time on curves back roads and 10% on the freeway, the reverse is probably closer to reality.

NYC993

I think it's toe issue. My inside wear picked up significantly when the steering tie rods wore out and presented some play.

Spyder_Man

Well the votes for the 'toe' have it!