17 vs 18 on 335

[hemismith]

I'm debating whether to go with the standard 17" wheel size (225/45) or 18" (225/40) on my 2008 335ix. I had a 328 with the 17" ContiProContact SSRs and just switched to the 335 with the 18" staggered setup and Conti Extreme DWS. Despite the lower profile I don't have the steering feel I had with the 328, and I'm wondering if that's because they aren't run flats or if it's because of a different steering system or what.

I'm debating whether to go the RFT route still; I know it's very controversial. To me the SSRs rode fine, perhaps because of the size. But on an 18 I assume they will be harsher. There are a number of advantages with 17s -- lower unsprung weight, lower cost, better pothole resistance, and more. They are both common sizes so lots of options (except in RFTs of course).

So I'm trying to get some feedback on the difference in feel and performance between the two sizes, and any other advice from anyone who's had both on the same car. Thanks.

[ezbmr]

Runflats are notoriously harsh and DWS are notoriously soft. It isn't so much the wheel size but the tires. The 17s will have all those advantages to them. If you want more feel, pump the DWS up to 40 cold, even 42, trust me they need it. If you want to get a firmer tire, get something else, it is a soft sidewall issue, not a rim issue. Hankook V12s and the Continental DW line are known for having soft sidewalls. The advantage is they are softer on the road, but they suffer on turn in. I have been recommending Bridgestone S-04 because of the bang for the buck.
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[hemismith]

Runflats are notoriously harsh and DWS are notoriously soft. It isn't so much the wheel size but the tires. The 17s will have all those advantages to them. If you want more feel, pump the DWS up to 40 cold, even 42, trust me they need it. If you want to get a firmer tire, get something else, it is a soft sidewall issue, not a rim issue. Hankook V12s and the Continental DW line are known for having soft sidewalls. The advantage is they are softer on the road, but they suffer on turn in. I have been recommending Bridgestone S-04 because of the bang for the buck.

Ah, thanks, good to know. Normally I would have expected an 18 to better feel even if it weren't run-flat. I was learning towards the DWS because of their good winter ratings, but I think I'll explore some other tires and pressure changes as you suggest.