Okay i realized more and more i read that most m3 owners are going towards the 18' rims rather than the 19's!!
i mean of course there is two big 20' m3 rims owners should shoot themselves but at the same time, what exactly is the reason behind choosing 18 9.5 over 19 9.5??
I'm not sure I can completely agree with this. "moment of inertia" suggests differently.
And a wider tire and rim certainly can aide in traction. Where a thinner W&T might start to somewhat break traction, a wider combo would hold at the thresehold.
Smaller means greater acceleration too. If the two wheels, 18 and 19 weigh the same, the smaller diameter of the 18s is, in effect, the final gear. You'd have greater acceleration, though a slightly lower potential top speed.
If I raced an identical car to mine with 17s, I'd win...coz I'm on 16s. Also, the more weight you have further from the axle, the more power it takes to move it...or something like that. I didn't take physics, but I did stay at a Holiday Inn once!
Doug, the smaller rim diameter is accommodated by higher sidewall on the tire. Regardless if you have 15s 16s or 18" rims, your overall diameter is still identical , which is 25" for E46 Non-M . For non-M E46 wheel tire combo must be 25" +/-2%.
For M3s the overall height is 26" +/-2%
Also, there are 20" rims that weigh less then 18" rims, and some 17" rims that weight more then 19" rims , see where Im going here ? You cant just say because this rim is bigger it automatically weights more then a smaller one .
Usually the overall diameter of the wheel stays the same because a smaller rim demands a larger sidewall. But, I do agree that the larger rim will add more mass away from the axis of rotation which will hinder performance.
One way to understand how two rims with the same weight but different diamaters would affect performance is to take a "thing" and tie a string to it. Then twirl it around in a big circle and then smaller diamater circles. The different forces you need to get the same rpm is what your car has to deal with.
The CSL has 19's....because it can.
so over all the diameter needs to be the same, but for weight saving and performance reason you'd rather have more rubber than metal? since rubber is lighter
Not necessarily. It all comes down to the rims. You can have 19" rims that weigh less than 17" rims. Chances are they're going to be really expensive. You don't want too much sidewall because it reduces steering response when trying to get the car to change direction quickly. The larger sidewall of a 17" rim will flex more than the sidewall on a 19".
A very very rough guideline for weight on wheels in the 17-19 range is anything that approaches 1lb per inch is very good anything under 1lb per inch is excellent and anything more then 1.5lb per inch is pretty heavy.
I have 19" rims and they can be a bit harsh. I expect that 18"s would give a little more cushion and be more comfortable while driving. However:
19" rims have tires with shorter sidewalls than smaller rims and this shorter sidewall flexes less under lateral load while cornering and improves handling for the car.
There is no doubt it is faster with the 18" rims and stock tires vs 20's and wide tires, but with as much as it breaks free I burn through tires more often than I go through oil changes using the 18's. With the 20's the weight seems to come into play both negatively for acceleration for sure, but also the highway ride seems to be better with the 20's. They look obnoxiously huge as well and as soon as I wear out the rubber it's back to the stock wheels.
I'm not debating that the smaller rims are better, I agree that they are and had I taken some measurements and done a little research before dumping cash on the 20's I probably would have just bought a nicer set of 18's and good rubber for them.
I have a ZCP which came with the CSL wheels and I thought they were pretty heavy.
I have since opted for a set of DPE MT20s which actually happen to weigh ~20-22 pounds which is actually lighter than stock and half an in thicker all around with the same staggered setup. So being 19x8.5 and 19x10. Thats what you get when you spend 5k on a wheel though. I also got a set of Bridgestone Potenza RE-11 with 245/35 and 285/35. Making for a pretty harsh ride day to day but damn do they grip. The RE-11s are a pretty heavy tire so I didn't notice a difference.
When it comes to performance I have noticed a significant increase in cornering ability mostly due to the tires and suspension setup. Negative camber up front (-1.5) reduces the understeer significantly and sharpens steering response. Along with fully adjustable sways allows for dialing every little aspect. It all comes down to what you want and are willing to spend.
For the most bang for your buck setup, a square 18" setup with coils at or slightly below (<1") stock ride height, stiffer and adjustable sways, poly FCABs, with the pins taken out of the stock camber plates for -0.5 camber is the way I would go. Better ride quality, less unsprung weight (compared to the 19s), sharper steering, and a more balanced car that won't understeer all over god's green acre into a tree.
Side note: "Lowering" an E46 M3 won't really help but reducing the center of gravity will. However you want to make sure not to make put the center of roll below the ground, possibly having negative handling effects.
depending on what you want your car to do, more rubber is better... sidewall height plays a very very important role in how hard you can hit a corner, and how much grip you have off the line.
buddy of mine has an e30 m3, and surprisingly enough... from the research and tips he's been given by well seasoned e30 m3 vets... 15 inch rims give the best performance for those cars... they need the rubber. if one were to ask me, i would have easily though 16's or 17's...
i will say, i think it is fairly easy to say that 18's in general, will perform better than most 19's... there is a such thing as not enough sidewall
most cars that are in car clubs and they show their cars get more points for 19" than 18" wheels most guys drop their cars to...
but if you live in the new york area tri state area.. the roads have alot of pot holes and bumps usually 18" wheels takes the potholes better than 19" wheels. but if you know wheels their are some 18" wheels like hre wheels that have the wheels with a softer metel i can tell you my 19" wheels that are kenisis are stronger than my hre 18" wheels..... but most guys by 18" wheels in bklyn because most co's wheels are stronger than the 19" wheels...then i say it is for perf. and to go faster.....
bob :thumbsup::thumbsup:
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