BMW M5 Forum and M6 Forums banner

1 - 20 of 49 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Is there a performance advantage in switching to a light weight 19" or 20" Rim or a larger rim just looks better?
 

·
Registered
Joined
·
2,817 Posts
I think only if they're lighter and wider - which is a very tall order!
 

·
Registered
Joined
·
1,558 Posts
Most, if not all, 19 or 20 inch wheels will be heavier than the stock wheels. But what you might do is swap your brakes for StopTechs or Brembo's and you might end up net neutral weight wise..

Stop Tech 4 wheel set up will not fit under your stock rear wheels but Brembo's do, with spacers for the front.

But in my opinion, any rim size increase should be for the eye candy appeal only.. Good luck in your choice

:M5launch:
 

·
Registered
Joined
·
2,289 Posts
as tire diameter increases especially on cars that have been previously optimized by a performance tuning entity (M, AMG, PVO, etc...) you will gain nothing and have alot to loose.

As diameter increases so does the rim mass of the wheel and the sidewall of the tire also decreases. Sidewall flex is a bad thing in most cases but going past a certain point especially in the 18"+ range is asking for problems.

18-19...no bigger.
 

·
Registered
Joined
·
1,316 Posts
M Power said:
But what you might do is swap your brakes for StopTechs or Brembo's and you might end up net neutral weight wise..
:M5launch:
Rotating mass will degreade performance. A heavier wheel with lighter caliper would still degrade performance since the caliper is not rotating mass, only the wheel/tire/rotor, and all of those are getting bigger...

Right?
 

·
Registered
Joined
·
268 Posts
rims on the rear of formula one cars are 13"--and feather light--so this tells you something about rim size for performance. race cars rarely go over 18"--even street exotics--mostly run 18" rims from the factory. however, the push for asthetics is high for consumers--the carerra gt has 20" on the rear i believe. with that much power you wouldn't notice the difference--but racers still use smaller diameters.

20" rims on an m5 would be hideous in my opinion.
 

·
Moderator
Joined
·
10,442 Posts
like chris rock says, "look, they're spinnin' they're spinnin'" (it's funnier when he says it)...
mike
 

·
Registered
Joined
·
4,419 Posts
M-Fünf said:
Rotating mass will degreade performance. A heavier wheel with lighter caliper would still degrade performance since the caliper is not rotating mass, only the wheel/tire/rotor, and all of those are getting bigger...

Right?
Yes, but the Calipers are still lowering UNSPRUNG Weight. That is important for handling.

Taking 1 lb of unsprung weight off is worth taking 10 lbs of sprung weight off.


The other issue is, 19 and 20 inch tyres are heavy. Don't jump to the conclusion that because they have a smaller side wall, they are lighter. They're not. So even the tyres are adding unsprung and thatis not desireable.

Beyond 18 inch, you have gone past the point of diminishing returns. They make uber light, uber strong 18's.

That kills everything 19's have to offer.

19's and above are purely cosmetic. Granted, alot of them look good.

The question is, do you want your car to look great whilst you stand next to it, or would you prefer it looking good as you four wheel drift past someone in a corner? ;)

The age old question of, Performance/Practicality Vs Looks.

MJ
 

·
Registered
Joined
·
268 Posts
i have the dinan rims which are super light, just under 18lbs, at 18". they look great rolling and you can put 275's up front and 285s in the rear without rubbing. you can however, get light 19" rims as well. i looked at the HRE C21s at Bimmerfest in santa barbara and at 19" they are very light as well--about 19 lbs. they are a 3-piece wheel, and can be built to your specs. they looked pretty nice up against my white car. i have attached a picture.
 

Attachments

·
Registered
Joined
·
2,099 Posts
BTW, its not just unsprung weight and rotating mass that larger rims effect. The rotating inertia due to the mass being moved to the outer edge effects performance, steering response, and component life signficantly. A tire shop commented that 26's on an SUV may increase total mass from 60 lbs to 160 lbs on each corner! The extra weight is highly stressful to bearings, suspension compents, steering gear, etc. He advises the owners against the big rims but they still do it for the bling factor.
 

·
Registered
Joined
·
5,078 Posts
alpineblue said:
i have the dinan rims which are super light, just under 18lbs, at 18". they look great rolling and you can put 275's up front and 285s in the rear without rubbing. you can however, get light 19" rims as well. i looked at the HRE C21s at Bimmerfest in santa barbara and at 19" they are very light as well--about 19 lbs. they are a 3-piece wheel, and can be built to your specs. they looked pretty nice up against my white car. i have attached a picture.
Sharp looking wheel, I like the high polished lip:flag:
 

·
Registered
Joined
·
400 Posts
Isnt this basically a discussion of how much acceleration your willing to give up for the looks factor?
 

·
Registered
Joined
·
12,398 Posts
Pete said:
Isnt this basically a discussion of how much acceleration your willing to give up for the looks factor?
Nobody has bought up the issue of keeping 20" rims from being bent when driving on public roads...

If it is a garage queen, shouldn't be a problem. If you live on a track, ditto.

As you loose sidewall you get a harsher ride and you put that rim closer to the concrete.

Personally, I think there comes a point where it starts looking totally non-functional and that's where I find it unattractive. For me form follows function...
 

·
Registered
Joined
·
1,856 Posts
Pete said:
Isnt this basically a discussion of how much acceleration your willing to give up for the looks factor?
My basic answer is 'none'. You're also making the assumption that the larger diameter wheel always looks better, and I don't necessarily agree with that.

My new K28s (should be here any day now...) are 18s, they (should) fit over the four-wheel Stoptechs and other than that I'm quite happy to preserve all the sidewall height I can get.
 
1 - 20 of 49 Posts
About this Discussion
48 Replies
30 Participants
Richard in NC
BMW M5 Forum and M6 Forums
M5Board is the best forum community for information on the BMW M5 E60 (V-10), E39 (V-8), E34 (straight 6), E28, F90 and F10. Discuss performance, specs, reviews and more!
Full Forum Listing
Top