Tire Wear Even Front to Rear?

[brock5ga]

03 Z4 3.0i Sport Package. Put on lift last week for oil change to find 2 bald rear tires. Purchased vehicle @ 12k miles ago. Negotiated front tires when purchased. Currently has oe run flats on vehicle all 4 locations. Rear tires looked good when purchased, but never measured tread depth to verify life. Going non run flat and have found some good rebates on 4 tire purchases. I thought I had read somewhere that these cars tend to use 2 sets of rear tires to a set of front tires, similar to my bike. If this is the case, I would just purchase 2 tires and use the remaining life of the front tires. If everyone's experience is that they wear pretty evenly, I will purchase 4 and take advantage of the rebates. May be able to offset the purchase with the sale of the fronts that are still about half life. Also have a set of BC coilovers that I plan on installing at the same time.

Thanks in advance for the input. Could not find any info searching the forum.

[seank]

Hmm. Mine has always been even or leaning towards wearing the fronts out first due to having more camber. That being said, I don't drive around spinning my rears.

[XMetal]

Just replaced my OE rears, while the OE fronts still have about 30% threads left.

[brock5ga]

Originally Posted by seank

Hmm. Mine has always been even or leaning towards wearing the fronts out first due to having more camber. That being said, I don't drive around spinning my rears.

Not spinning rears either. Just unsure what the tread depth was in the rear when purchased. At glance, they looked fairly equal to the fronts that had just been replaced. Camber at factory specs. Not tracking car, just moderately aggressive street driving.

[Kgolf31]

Originally Posted by brock5ga

Not spinning rears either. Just unsure what the tread depth was in the rear when purchased. At glance, they looked fairly equal to the fronts that had just been replaced. Camber at factory specs. Not tracking car, just moderately aggressive street driving.

What is toe at though?

Toe is what chews the tires, camber has very little to do with it.

[The HACK]

Mixing compounds front and rear isn't ideal for performance.

[brock5ga]

Originally Posted by Kgolf31

What is toe at though?

Toe is what chews the tires, camber has very little to do with it.

Tread never chopped. A little more wear from the inside to the outside due to the negative camber. My question was geared more towards the wear rate of the tires, not the wear pattern of the tires. Broke down and ordered a set of 4 Eagle F1 Asymmetric 2's. Should be in this week. Discount through work and 4 tire rebate made it more than worthwhile. I am going to try to go in on my day off next week and install the BC Coilovers and tires. Thinking about lowering car @ 1 in. Will set alignment specs then.

[Kgolf31]

Wear from the inside is contributed to toe. Not just camber.

I'll be willing to be your toe is what is ultimately chewing the tires

[brock5ga]

Originally Posted by Kgolf31

Wear from the inside is contributed to toe. Not just camber.

I'll be willing to be your toe is what is ultimately chewing the tires

Never checked the alignment since purchased. Tires always looked to wear pretty even. Inside edges not much lower than the outside edges. The coilovers have been sitting in the shed since about March. I guess the tires are what I needed to get these and the alignment into action. I have been driving the car a lot since all we have had in GA lately is rain. Bike has been parked and car has been used for work. Unfortunately it is not worth putting on the alignment rack to take before readings since the shocks are getting replaced. I would be interested to see where it was at, just not enough to set it up twice.

[StickMon]

As you've probably gathered by now, there's no one answer.
It's going to depend on how you drive and how your suspension is set up.
Personally I've never run much negative camber, and while I don't often light 'em up, I do tend to let the tail run wide coming out of corners.

Every car I've had, including 3 Suburbans, has run about 2 sets of rears for every set of fronts.
(Or would, but most of my cars weren't staggered so I could rotate.)
I would say your situation is "not abnormal".

[brock5ga]

Went in today to mount tires and change suspension. Curiosity got me so I did take some before measurements, loaded as per specs. I also wanted to see a baseline as the settings for the 3.0 with Sport Suspension as listed in the Hunter machine are rather aggressive, though this is obvious when looking at the negative camber very evident in the rear tires. Before readings, rear camber even at -3.0. Left toe at .19 and right toe at .38. Right rear was showing more wear than left rear. Left front camber at -1.3 and right front camber at -2.4. This matches the feathering on the inside edge of the right front tire. Front toe even at .14 and .13.

Started off an inch lower and subsequently ended up raising back up to about 1/4" lower than stock after using the speed bumps at work as a guide. Ended up setting front camber at -1.3, which is at the negative side of the stock settings and the rear at-2.7, which is at the positive side of the stock settings. Front toe centered specs at .12 and rear toe centered at .20.

Here is my question now. What is the reason for the .20 toe in on the rear? This seems a little much, but I am sure there is a reason behind it. I am going to let the suspension settle for a couple of weeks and recheck ride height and alignment settings. Just curious if I want to tweak anything. Also thinking of moving the front toe to the outer limit of specs at .05. I don't track the car, just a little playing on the back roads. Car did handle extremely well on the way home and the tracking was gone. Very happy with the changes thus far.

[seank]

I toe-in rear 1/32 per side, 1/16 total. I don't know what that equates to in degrees.

Benefits:

More straight-line stability
More traction out of the corner (able to get on it sooner)
More stable during heavy breaking

[brock5ga]

http://www.smartracingproducts.com/s...able-cw-v3.pdf

Best chart I could find. Looks like 1/32 equates to .1 in degrees on an 18" wheel. I will probably give everything a couple of weeks to settle in and do a final tweak. Seank, thanks for the benefits list. This is the first car I have owned that the suspension is capable of outperforming the engine. I'm used to domestic cars with solid axles and worrying more about throttle so they don't break loose in the turns than of the steering position. Even though I have had a lot more powerful vehicles, this is at the top of the list of the most fun to drive.