Kennetht638

iTrader: (2)

Hi guys, I'm looking to get some new rallycross tires, and since I determined that a downgrade to 15" wheels for rally tires was too much trouble, I'm looking in the other direction at truck-ier tires and heavy duty snows for the stock 18's. So...I'm wondering if a 225/60/18 will fit all around without drama. I'm currently considering Firestone Winterforces, which they claim has a 25" diameter (which I think is wrong because the stock 225/45's are 25.9"), and the Cooper WeatherMaster S/T2, which is a more likely 28.7 inches. Will a tire this tall fit under the stock fenders? Thanks.

imput1234

iTrader: (6)

I don't know, but 16's do fit the car maybe you want to go that way?

pdxhak

iTrader: (2)

You may run into brake clearance issues with 15" as well.

Kennetht638

iTrader: (2)

I know that 16's will fit with an AT brake downgrade, and to get 15's, it's necessary to remove material from the lower attachment point of the front upright as well as the two rearward attachment points of the rear upright. I really don't want to have to do the brake downgrade just to get 16's and still be unable to run rally tires, and I don't want to grind away suspension bits without having some spares lying around. Also, since this is also my autocross ride, it would be nice to be able to keep the car in BS. In fact, the whole point of running 225/60/18's is to be able to remain in the Stock RWD class in Rally-X.

Anyway, today I removed one of my shocks, taped 2" foam pipe insulation to the top of the tire and cycled through the suspension. It looks like the added diameter would be disastrous, as it would rub the fender liner when turned, and it would crunch the fender pretty badly under compression (also when turned). So...I guess I'm sticking with my Hankook Icebears.

romycha1

Are you sure? Doesn't the base model 8 come with the same brakes but 16's?

PBlue

iTrader: (1)

no, smaller front rotors on the "non-sport" suspension.

r0tor

iTrader: (1)

i believe there will be a few more snow tire type options if you go to 17's

Kennetht638

iTrader: (2)

Yeah, but I can get a set of 18" Weathermasters for $375 while staying in Stock RWD, while 17's will run me about $500 for wheels and $480 or so for tires in addition to bumping me into Prepared RWD and into competition with guys on rally tires.

Jax_RX8

Wow - all these answers and no one even attempted to answer his original question.

Let me try.

The tire height for a stock tire 225/45-18 tire is 101.25mm.
If you went to a 225/60-18, tire the height is 135mm.

135-101.25=33.75mm or about 1.33 inches taller (Up and down) - so the tire will extend 1.33 inches higher into the fender well and the car will sit 1.33 inches higher off the ground for more ground clearance (I am assuming that is one of the desired impacts).

So, as far as the fender wells are concerned, front and back clearance should be fine, it would be the additional height to consider. Assuming you are running on stock springs at the stock ride height, it would be equivalent to lowering the car 1.33 inches.

With this in mind, I can tell you that I have my car lowered 1.4 inches front and back with my lowering springs and have never bottomed out - however I am not racing.

Also the stock shocks have bump stops, so I would think they would stop the suspension compression before the tires hit the inside top of the fenders with only the 1.33 addition.

Now if you have lowered your car, you need to add the lowering to the total, and may have an issue.

Hope this helps

kersh4w

iTrader: (3)

i really doubt he has lowered his car, he would want extra clearance for rallycross, not less.

Kennetht638

iTrader: (2)

Jax: Thanks for the response, but I don't think that the taller tire is equivalent to lowering the car. When you lower the car, the suspension sits in a different spot in its travel at ride height. If you haven't changed your shock lengths, your suspension travel is exactly the same as mine. You just have more rebound travel and less compression travel. So...if under full compression with the wheel turned, you have 2" of clearance to the fender, this would work, but I don't think there is that much clearance. I may be wrong since I checked with the shock removed, but it seemed pretty unlikely. If you have any further insight, I'd really appreciate it. Thanks.

Jax_RX8

I agree, but I was not talking about suspension travel - I was talking about the amount of room under the fenders before you hit the wheel well liners - lowering puts your tires initially closer to the wheel well liners just like using a taller tire such that it takes less suspension travel before your tires come in contact with them.

Anyways, hope this helps some.