z4 suspension sport, hard on my back

[kmancars]

I bought a 05 Z4. I am new to sports cars I need some help. The car is very fine, but the sport suspension on 18" run flat tires! I must admit my back is not the best, but at 62 I am in good shape. What can I do to soften the ride? The ride now is unforgivingly stiff and choppy. The car has only 34k miles on it. Thankyou for your help.

[CalRick]

The first change would be to replace the runflat tires with conventional tires - RFT sidewalls are notably stiffer to support things without air. My wife couldn't stand riding in our Z with the RFT's after her neck surgery, but is ok with conventional tires on it. Of course, without the RFT's you should get a compact spare (eats up a lot of trunk ******* or a mobility kit for emergencies.

You can also check the reviews on tirerack.com to get a feel for which tires ride better. A switch to 17" wheels and tires can also help with the ride for the cost of new wheels and a bit of loss in handling response.

[kmancars]

I see your point on the RFT and wheel size. Where would I buy 17" factory rims, used, or trade for my 18" elipticals? I am worried about the hard ride solution as a newcomer to BMW. I shelled out some sizable money for this car, without a clear understanding of sport suspension or RFT's.

Could I go even further to a 16'' stock rim? Advice from any other members will be appreciated.

Thank you again Cal Rick

[mister_roger]

I second that the RFTs have to go. You will feel a signficant ride quality difference once you switch. Even when I upgraded from 16" wheels w/ RFT to 18" wheels with non-RFT, the ride quality was vastly improved. You won't regret it.

If you are concerned about getting a flat tire, then my suggestion would be to keep a portable tire pump + tire patch kit, or an OEM mobility kit.

[kmancars]

Thank you as well Mister Roger I am in this to learn. ZPOST is so helpful.

[CalRick]

I'm not sure if 16's will fit your car or not - is it a 2.5i or 3.0i ( the brakes are bigger on the 3.0i, but I'm not sure if big enough to make a difference on a 16" wheel.) Tirerack.com has a lot of these specific fit answers. I can't say how much difference the smaller wheel/taller tire combination will make vs. the RFT vs. conventional tire since I haven't gone that route. If your existing tires are near replacement time, then the cheapest thing to do would be to simply replace them for conventional tires and see how they work. If they are still too stiff, you can replace them with new wheels/tires and sell the 18's to someone who wants to upgrade - almost everyone wanting to upgrade wheels/tires wants to go to larger wheels, so that shouldn't be a hard sell.

You can check ebay, the local recycler ads or any of the various BMW boards (bimmerfest, bimmerforums) to see if anyone is selling OEM 17" Z4 wheels. There is also a pretty active Z community here in socal - desert poppy tour this weekend - so you may be able to meet up with some others and possibly sample other Z configurations.

[vachss]

You could almost certainly find any number of folks around here willing to trade their 17's for your 18s, but realistically you should try non-RFTs first as that will make a bigger difference.

[Incompatible]

Originally Posted by vachss

You could almost certainly find any number of folks around here willing to trade their 17's for your 18s, but realistically you should try non-RFTs first as that will make a bigger difference.

X2 Good advice, no need to spend any more money then necessary. Should you decide that the 18's still don't give you the comfort you're looking for, then selling/swapping your wheel/tire set will not be a problem. You might even get some money in the transaction.

[kmancars]

Thanks again for the advice on tires and wheels to soften my ride, kmancars