Alpina wheel switch

[Z8ER]

I'm thinking of switching from OEM wheels to the 20" Alpina wheels on my 2002. (I know that folk have varying opinions about the "cheese graters".)

I have a few questions that I hope someone can help with:
1. Are any modifications (such as spacers) necessary?
2. Lighter wheels are preferable with our strut tower issue. The Alpina wheel is larger (and wider - 10" in back). Does anyone know how the Alpina's wheels compare in weight to the heavy 18" OEM's and other aftermarket 20" wheels?

I read somewhere on the forum that the Alpinas had suspension modification to take into account the thinner sidewall, but it seems that shouldn't be necessary because of the more compliant non-run flats that the Alpinas were carrying. Would any suspension work be necessary or recommended with this combo?

I appreciate any thought?

Thanks.

[SBoysky]

I have thought about this, as it is in keeping with the OEM nature of a collectable.
It sure is purtee.

I wonder if there are any others who have done the diligence of "retrofitting" these wheels.

[Grease Monkey]

As far as I know, you should be able to install the Alpina V8 Roadster wheels on a Z8 with no issues. While the Z8's suspension was modified by Alpina to create their version, the differences relate to springing and dampers, not hubs, so they should just bolt right up. Whether you will like the ride quality is a different matter. While it is true that the OE runflats on the Z8 have a relatively stiff sidewall, those sidewalls are much taller and thus more flexible than the ones used on the Alpina. As a result, the Z8 tires are more forgiving than the Alpina's 20"ers. That's why, to counteract the increased sidewall stiffness, Alpina used a softer spring to keep ride quality acceptable. A number of Z8 owners have installed 20" wheels and tires of one type or another on their cars and most seemed pleased with the results, so it's really a matter of personal preference, but the Z8 will have a stiffer ride quality with the Alpina wheels and tires. Whether this will exascerbate the shock tower deformation problem is hard to say but unless the Alpina combo is significantly lighter than the OE Z8 combo, I would expect the forces transmitted to the towers to increase. If BMW has done its homework with the Performance Package, this may not be an issue of concern. Personally, I think 19" wheels and tires are the best way to go on a Z8 and the lighter, the better. What you really need is to have someone pull a front and a rear wheel off their Alpina and weigh them for comparison. The OE front combo on a Z8 weighs 59 lbs. and the rear combo weighs 64 lbs. Hope this helps!

[SBoysky]

GM,
Thanks. Your feedback puts it together.
I'm going to call Tire Rack and ask them if they have any feelings as to which of the performance tires (Michelin sports or Bridgestone RE050A) might be expected to have the best ride. (Though I doubt that a good ride translates into less force to the shock tower)
If you have a chance, please let me know if you know of anyone who has put softer springs on their Z8 to compensate as the Alpina did for bigger wheels.
Thanks again.
Syd

[Grease Monkey]

Alpina used softer and shorter springs on the Roadster V8. 15mm shorter in Europe and 10mm shorter in US. They also changed the damping rate to fine tune the ride quality. If you want to duplicate their efforts on your Z8, you should be able to order new Alpina struts and springs that will bolt right up. I'm not aware of any aftermarket company offering softer springs for the Z8. If you like the Alpina wheels, I suggest you try them on the car without changing the suspension and see what you think. The handling should be noticeably better (shorter sidewalls, more rubber on the ground, better rubber compound) and the ride noticeably stiffer. If you don't like the ride quality, substitute the Alpina parts. Without knowing the weight of the Alpina wheel/tire combo it's hard to say what impact their installation will have on your frame and towers, but I'd highly recommend installing the Performance Package as a prophylactic.

[Z8wannabe]

Z8er
I've done it and the ride is noticeably different. Stiffer and tighter ... I love it.

[SBoysky]

Funny that.
I thought that the replacement of non-run flats with standard tires would negate the thinner sidewall to provide a similar ride.
It sounds like it must be more of a bear on concrete highways!

[SBoysky]

GM,

I heard from someone that the handling on the Alpinas is desirable to the standard Z8 (because of the Alpina set-up with slight lowering). They also said that the Alpina springs are as stiff as stock.

Assuming the replacement to the 20" Alpina wheels, how would you compare the Alpina to the stock Shock/Spring set-up for the Z8 in these two categories?

Handling?
Ride?

Thanks.
Syd

[Wldeyefoto]

I have never driven an Alpina so can't comment on what the handling is like. Lowering the car and running lower profile / wider non-runflat tires with a better rubber compound should produce an improvement in handling. Alpina did soften the springs and recalibrate the damping to compensate for the stiffer sidewalls of the 20" tires and I have read that the ride quality was better than on the Z8, but that is a subjective thing. Grease Monkey

[SBoysky]

I heard something new recently.
That the shocks were not dampened for comfort, but rather to compensate for the weight of the Alpina motor...