Rear wheels also fit on front? (Z4 Coupe 3.0si)

[Louv]

Apologies if this has been asked before... I looked, but couldn't find the answer)

Can the Z4 [Coupe 3.0si] handle 18x8.5 wheels on the front? I want to balance out the understeer for the track, and want to get rid of the staggered 8 vs 8.5 wheels.

I know I can go to all 8" wheels, but can I go to all 8.5"?

Thanks.

(if anyone has an inexpensive set of lightweight wheels, I'll be in the market for a 2nd set really soon now! )

[Wondermike]

Wouldn't fitting wider tyres on the front increase the understeer? Certain models of the Lotus Elise have a front tyre size of 175 wide, for better handling.

[Louv]

Increasing the front tire width decreases understeer, and increases oversteer. (it gives you a little more traction in the front)

BMW builds in a certain amount of understeer in all their cars, because it is "safer" for most drivers on most roads. Oversteer in most people's hands will only get them in really serious trouble.

But I want more neutral handling on the track. So I want to get rid of the staggered wheels.

--- But now I need to change the question... Further investigations shows me that there are no R-Compound tires in size 255/35 R 18. So I either need to go to 265/35 R 18 or drop down to 225/45 R 17 tires on 17" wheels.

Question #2: Will 265's fit in the Rear (and front?)

[Curtis]

My Alpina has 265/30/19 rears as standard and I recently changed to 275's so I/m sure they should fit yours ok. My suspension is very low too but it still hasn't created any issues. I've had to leave the fronts as 235/35/19's because of clearance issues but I'm sure I could go wider if I lifted the suspension a little. Not going to though!

Have you removed the dowel on the top of the front strut turrets and pushed the struts inboard yet? This gives you about 1.5 degrees negative front camber and greatly improves front end grip on cornering. Costs nothing too.

[Wondermike]

Louv thanks for the update.

Curtis 275 tyres - are they on standard Alpina 19s?

[Louv]

My Alpina has 265/30/19 rears as standard and I recently changed to 275's so I/m sure they should fit yours ok. My suspension is very low too but it still hasn't created any issues. I've had to leave the fronts as 235/35/19's because of clearance issues but I'm sure I could go wider if I lifted the suspension a little. Not going to though!

Have you removed the dowel on the top of the front strut turrets and pushed the struts inboard yet? This gives you about 1.5 degrees negative front camber and greatly improves front end grip on cornering. Costs nothing too.

Thanks for the info.

No I haven't done the camber adjustment yet. I'm not quite ready to track this car, I'm just getting all the ducks in a row.

I'm still running my '88 M6 as a track car. The Z4 will be its successor.

[tehdarkstar]

The problem with putting wider tyres in the front is that steering will be less imediate, which may make harder for you to be smooth in your steering inputs.

What I found with my M is that driving through corners at high speed it tends to understeer, but it is very throttle sensitive, so giving a bit more throttle you can get power-oversteer and the car seems to grab the line you want to follow.

I can't say how this will work in the track, as I haven't done a trackday in my car yet, but I have tested in some roads that I know well and found the handling to be very adjustable (albeit not neutral), so I will take it to the track and get a proper feel of how it goes before changing anything.

[Top pup]

I'm running 245/35/19F and 275/30/19R and have no clearance issues, 245 looks to be about the widest you will get away with on the front.

[Louv]

As a side note, I run "Rear" wheels on all four corners of my e39 M5, with 275s. It requires a 3mm spacer on the front wheels, but the handling is noticeably improved.

[Curtis]

Louv thanks for the update.

Curtis 275 tyres - are they on standard Alpina 19s?

Standard was 265/30/19, I just went for 275's this time around.