E60714

If I were to go from the stock OEM 17" to maybe a 19" or 18" setup, what are the performance implications? Rough ride? Slower acceleration?

v_therussian

First aspect to consider is weight. However, almost before you delve into it, a disclaimer should be made that some 19's are probably a lot lighter than your stock 17s (especially, if you'll be going from RFT to non-RFT in the process). But weight is the most important aspect as it directly affects the unsprung weight, which can cripple your acceleration.

Second, you should look into your overall rolling diameters. Going from 18s to 19s or 20s, the change in rolling diameters is usually negligible, but it does affect your performance and your speedometer accuracy. I recommend you use a calculator to determine the difference between your current overall rolling diameter and one you'll be switching to. This calculator will also tell you how much off your speedo will be and in which "direction".

Finally, when looking at ride quality, think of it either as a "loss of comfort" or "gain in sensitivity and control", but you'll be getting much more direct communication from your steering wheel. BMW has a pretty sensitive steering to begin with, so imagine your steering in HD and you'll get an idea. To some this might be a problem, to others - solution. I tend to side with the latter, but there's no shame in either.

danzanchy

I think that depends on the weight of your wheels plus the thickness of your tires... u usually want to go with a setup that has the same (or close to it) diameter as the stock specifications.

Edit: V beat me to it with a much better (detailed) response... read his and ignore mine

v_therussian

Actually, you reminded me of something else I originally forgot: even though this is both - beneficial and detrimental, an increased contact patch will make a huge difference. On one hand, larger contact patch means more friction, translating into more resistance for the car to overcome. However, in a performance-oriented sedan, such as an e60, it is probably negligible and the gains in sensitivity, not to mention the considerable expansion in the car's handling "limits" far outweigh any detrimental effects a larger contact patch might have.

danzanchy

well put

Phantom Mark

Also a problem with larger rims is that the tyre sidewalls become thinner proportionally.

Thinner the sidewall the less rim protection, the less tyre roll in hard cornering, thus more precise handling, however when you go over the limit shallower side walls snap back much harder, it gives you less warning.

This is not generally a big problem unless you start fitting staggered offsets with large width rears on 19's or 20's tho.......

mnmike

You really get what you pay for. Most larger wheels will weigh significantly more which will result in slower acceleration, worse handling and like you mentioned a larger rim will mean a slightly stiffer/rougher ride.

If you spend the big bucks you can get larger and lighter wheels which will improve your performance overall. I believe discount tire direct tells you wheel weights right on the website - so go do a little searching and see how much those weights vary. We recently talked about how they had a special on RAYS Engineering forged wheels for dirt cheap that were super light. Many of the cheapo wheels weigh nearly twice as much!!

One good route is to find some oem (not replica) wheels. Generally speaking oem wheels are pretty light so if someones getting rid of their stock 18's or 19's it could be a good upgrade. Just remember if they're replica's they weigh a lot

flyingpuck

Implication of larger wheels?? Usually larger expense!

Brit_in_NJ

...and smaller wallet!

luigi524td

Going up to 18" wheels may bring a sight increase in ride harshness and a slight improvement in handling. Choice of tires (brand and type) may have as much to to with ride and handling as wheel size for this upgrade. However, IMHO moving up to 19" with the appropriate performance tires (RFT or conventional) dramatically increases the sharpness in handling as the sidewalls are shorter and stiffer. And the ride will be harsher, too. You also increase the probability that a pothole will eat your wheels and tires faster than a Democrat's legislation will eat your $$$.

As for changes in acceleration - if you maintain your original and optional tire size(s) according to spec there is likely to be no discernible change since the rolling radius will remain the same. And except for a slight decrease in weight that might come from lighter wheels, higher performance tires also tend to have higher rolling resistance - that's why they are so grippy ... so one may offset the other.

I think you need to balance your driving needs with wheel/tire size. For many, appearances add to the equation as does the depth of your budget!

Good luck making your decisions ... you'll get lots of good advice and valuable opinions here