How does front tire width affect car characteristics?

[Villanuevas_BMW]

If the front tires or wheels are widened on an FR car, what happens? Pros and cons? Im guessing better braking and cornering with the correct camber but a drop in steering. What else?

[Suneal]

It'll understeer less, I believe.

[Alex Mc]

Originally posted by Villanuevas_BMW
If the front tires or wheels are widened on an FR car, what happens? Pros and cons? Im guessing better braking and cornering with the correct camber but a drop in steering. What else?

Typically when you increase the front tire width you gain several advantage, which do lead do less understeer as mentioned. This is because you are increasing the front grip, thus the front tires can hang on for longer.. too much front-end grip, however, and the car will oversteer. Also, you get increased/sharper turn-in response and due to the larger cross-section your braking ability should also be increased. The disadvantages are the increased drag and weight from a heavier/wider tire, but the bad is far outweighed by the good in most cases. Dinan runs 275's up front on their tuned E46 M3's.

[Villanuevas_BMW]

Originally posted by Alex Mc
Typically when you increase the front tire width you gain several advantage, which do lead do less understeer as mentioned. This is because you are increasing the front grip, thus the front tires can hang on for longer.. too much front-end grip, however, and the car will oversteer. Also, you get increased/sharper turn-in response and due to the larger cross-section your braking ability should also be increased. The disadvantages are the increased drag and weight from a heavier/wider tire, but the bad is far outweighed by the good in most cases. Dinan runs 275's up front on their tuned E46 M3's.

That totally answered my question.
Now how about this

A car with an 8" and 8.5"rear setup ran fine and was balanced in and out of a turn. Now the driver got new wheels in the back and is now running a 8" and 10" in the back. Since the rear traction patch is larger it will slide less and will hold a desired line in and out of a turn, however there is no change up front, therefore causing the car to understeer. Is this neccesarily true?

[postmaster]

This page is really helpful

http://www.bmwe30.net/cgi-bin/datacg...087&Section=05

[Villanuevas_BMW]

Once again, thanks postmaster

[Matthew C Smith]

Just another thought, the larger front tires may increase steering effort.

[Villanuevas_BMW]

Ya I thought of that, its bad enough with 195's up front with no power steering.

On the chart that Postmaster posted under the E30 link, it said that the more downforce through aerodynamic adjustment in the front will lead to understeer and the more downforce on the rear will lead to oversteer. I thought the exact opposite

[kiley_sean]

Villanuevas, when are you going to sell your '02?!!!!
That's one smooth looking body on that thing.

[Techno Violent]

I run 255/35/18's on 18x9's up front w/ 12mm spacers. That's A LOT more width/track than stock 225's on a 7.5" rim. Wider is better. Handling is phenomenal for a street car. Great turn-in, precision, feel, etc. No downside, except for increased tram-lining and bump-steer on bad roads.

[C ///M]

I went from 195's to 235's. I have to agree 100% with above post. Only down sides were tram-lining and bump steer, as stated directly above.

[OldSkoolBmw]

If ur talkin about street tires... I run a 205-50 on the front of my 02 and a 225-50 on the rear.. same setup for hoosiers and autox.. works great.. the steering is a bit heavy but no toe helps..... the track car sits on some nice 0 offset zender 15x8's... deep dish.. with what would be like I guess a street tire 245-50 sized race slick on it.. once moving the car handles well.. I don't see why you need a 10" wide tire in the back.. even with 220+HP in this 4 cylinder it's hard to generate rear traction issues

[Villanuevas_BMW]

I got my 215/50/15 a month ago and im really happy with it. braking is better and response too. Also its a better match up with my 225/50/15 rears and with my new adjustable front coilovers, it fills the fender gap A LOT better than my 195's. Also my front is not dropped anymore so there is less weight there at level sitting. Thanks guys, this thread helped. Im not really going to have 10" rims in the back, i just used that as an example.

Before

After

[OldSkoolBmw]

Are those alpina 3pc wheels on there? Needless they look sweet man.. nice setup.. to bad ur in cali or I'd race ya at the next track day...