Uneven Tire Wear... Please HELP!

[presidentg]

I have a G35 Sport Sedan, its lowered, and has a suspension kit on it. I have to buy new tires every three months. My tires on the car are:

F- 245/45ZR/17R-255/45ZR/17

My tires wear to fast. Are my tires to big for my car? Should I have my car raised? Should I get a new suspension? HELP!!!!

[ArizonaG35]

Welcome to Nicoclub Mr. President!

Sorry to hear about your premature tire wear, but I'd say that unless you are driving 1,000 miles a week then 3months is definately too soon to change tires. Get the alignment checked and SOON! Is the wear on any particular spot on the tires? Outside? Inside of the tire?

More info please!

Welcome again!Dave

[presidentg]

Thanks for the reply! Its wear on the inside of the tire. I went saturday to get an alignment but they said they couldn't do it because of the suspension kit. I dont know the details about the suspension kit.....

P.S. its Ms. President....

[ArizonaG35]

P.S. its Ms. President....

Not yet it's not! We still have a couple more delegates to count before that happens... Just kidding!

I know that some lowering kits require adjustment to the toe and camber to prevent uneven tire wear and ensure proper alignment, but I believe that this is dependant on how lowered the car is and what type of lowering springs you have... Check out the search button at the top of the screen and see if there have been any other previous threads concerning this topic. You should definately not be burning through tires that quickly... TOO EXPENSIVE! I'm sure a tech will be along shortly with more info soon...

Let us know what you find out...Good luck and WELCOME!

[rn79870]

P.S. its Ms. President....

First of all welcome to the forum. We have a pretty good time around here.

I think I have to agree that with a modified suspension, you can't expect the tires to last as they were designed to. I can't point at the suspension as the problem, but I'd bet it was. 3 mts is way, way too often. Some of the people report over 40,000 miles on a set of tires.

Dave (ArizonaG35) gets a little confused about the male/female thing. We'll speak to him.

Again welcome.

[ArizonaG35]

Here's a good start on recent topics... this guy seemed to have a similar problem as you... maybe this thread will be of assistance.

Yeah, sorry 'bout the Ms/Mr mixup... I mean well, I just sometimes need a little to keep me in line... Good luck!

zerothread/298288

Dave

[Sentientbydesign]

You're probably running 2 or 3 degrees of negative camber when you lowered the car.

In order to fix that you'll have to raise the car OR get a camber kit. It's not going to be cheap, but it will bring the angle of the suspension back within spec so that the tires will sit flat on the ground instead of at an angle.

Do an ebay search for G35 Camber Kit. Or if a shop did your suspension, them for not recommending a camber kit to you.

[presidentg]

I think you hit the nail on the head, my tires lean inward. So you dont think the tires are to big? I should just raise it up? I think when I hit a bump the body of my car rubs up against the tire and it tears and goes bald. But I will look into having it raised... Thanks

[Sentientbydesign]

Hold on!!!

The tire wear isn't because the tires is hitting the body of the car, it's because the tires is only contacting the pavement on the inner portion of the tire.

Think of it this way. If the tire is straight up and down (zero camber) then the tread has weight distributed evenly. When you tilt the wheel/tire inward (or outward) the tread also changes it's contact with the pavement meaning that one edge will have a lot of pressure and it will linearly decrease until you get to the other edge that has little to no pressure on it.

You need something like this:

http://cgi.ebay.com/ebaymotors...ZWD1V

They allow for +1 degree of camber which will probably put you into spec so you don't keep wearing through tires.

[C-Kwik]

Depending on how much you lowered it, you may have a compound issue going on. Few, if any, production cars the steering arms on the same plane as the lower control arm. Its typically close enough that suspension movements cause unnoticable amounts of bump steer, but stray too far from the OE suspension height and toe may be changed. In other words, your toe setting may be off as well.

Which leads me to another point. Lower too much and even if you adjust toe to be correct when static, the dyanamic rate of change in toe (the toe change as you corner or hit bumps) may be altered to the point where you may get bump steer and/or poor handling.

[Sentientbydesign]

I can't visualize c-kwik and you're one of a few people on this forum that I like learning from.

Any sites with pics for me to visualize?

[C-Kwik]

It is hard to visualize. I recall when I was reading through a suspension book I have many years ago, I had a hard time understanding what it was talking about as there were no pictures.

Did a quick search on bump steer in google and found this:

http://www.mustangandfords.com....html

Here's the shortened version:

In the following picture, the suspensions is at normal height. Notice the difference in angle and height of the steering tir rod and lower control arm.



Now, look at a picture of the suspension under compression. As the length of the tie rod and control arm are unchanged, they follow an arc that is dictated by the inner attachment point and their length. As the lengths in this case are different and the radius and center points are different, they will follow a much different path.



You'll notice the in this second picture that the line that represents the tie rod is no longer in contact with the steering knuckle. While it won't simply detach itself as the diagram might suggest, it will start to pull on the knuckle and depending on if the steering rack is located in front of or behind the wheel centerline it will cause toe-in or toe-out respectively.

Bear in mind their example is extreme as it represents an older car's typical design. Newer front suspensions will locate the tie rod and the lower control arm on a much closer plane so this is less of a problem than the older cars, but still a problem nonetheless. Especially when pushing the suspension's primary movements closer to the outer range of the car manufacturer's intended range.

[Sentientbydesign]

Awesome, I completely understand.

It would seem that steering control would actually degrade due to lowering the vehicle.

So in order to have suspension work on a vehicle that is low to the ground, the steering rack must be engineered to be perpendicular to the knuckle at the intended height?

[C-Kwik]

It doesn't have to be perpendicular. If the tie rod and LCA overlapped exactly (on the same plane) when viewed from the front or back, then they would follow the same arc and as a result, would not experience any camber change throughout the entire range of suspension movement.

If the knuckle itself stayed perpendicular to the ground throughout the range of movement (which is unlikely), then the tie rod and the lower control arm only need to be parallel and equal in length to each other. But the reality is the knuckle will tilt during suspension movement so that alone can cause some bump steer if the tie rod and LCA were not on the same plane.

[presidentg]

Oh my... the part is pretty expensive. How much will it help if I raise my car back up? Is that the best price for the part?

[Sentientbydesign]

If you raise it back up to stock height and get an alignment, you should have little to no camber wear and the stock tires should get you 20,000-30,000 miles.