Dboey

Am thinking to upgrade my stock rim and would like to know the pro and cons of 17 inch vs 18 inch rim (including performance). Thank you.

smokedmustang

iTrader: (7)

I think 18's are more for bling and 17's are the better performers in performance. (Less rotating mass).

Warrtalon

iTrader: (6)

There is a lot to it, and it's been discussed many times already.

Smoked, rotating mass is not determined strictly by the diameter of the wheel. The stock Enkeis are 17X8 and weigh over 20 lbs. My 18x9.5 Enkei race rims weigh 19.5lbs each, so there is less rotating mass. There are a lot of other factors, too, but I don't want to rehash what has already been discussed in depth. In fact, the thread directly below this talks about the same thing, so I'm baffled as to how the thread originator didn't see it...

smokedmustang

iTrader: (7)

Thanks for the clarification Warrtalon!

Dboey

Hi Warrtalon,

With your 18 inch rim, the weight is lighter than the stock rim and can I say that your car move off faster or similar to an evo with a stock rim. Personally, I feel that the 18 will move off slower than the 17 initially.

Warrtalon

iTrader: (6)

If it's lighter, then there is less rotating mass, which makes acceleration easier. Why would a lighter 18" rim "move off" slower? It wouldn't. Plus, the bigger rim can hold wider tires giving better traction.

theblue

iTrader: (1)

you can't just say a lighter wheel is better because it has less rotating mass..

the majority of the weight of a wheel is in the outside barrel. as you move this further away from the center of the wheel it will become harder to turn.

Warrtalon

iTrader: (6)

You also can't say all 17s have less rotating mass than all 18s, but comparing the weight of the wheels is good enough unless you want to get deeply scientific about it and know all the calculations (I don't).

theblue

iTrader: (1)

somebody on here must be good enough to calculate the exact amount lighter an 18 must be to match at 17? my guess is probably 5lbs. less to equal.

evobeaner

I would think the weight of the tires also contributes to your question.

theblue

iTrader: (1)

for sure.. but the driving fact is still that ouside of the rim is the heaviest part and matters the most.

Warrtalon

iTrader: (6)

5lbs per rim? I highly doubt that, and not all rims have the same % of mass in the outer rim. Some have more in the spokes than others, such as my NT03+Ms with the extra reinforcement bar that goes around the outside and connects the spokes together. There is no exact formula, because of this, but I'd much rather have an 18X9.5 rim that weighs 18lbs than a 17X8 rim that weighs 18lbs (or 20+ like the stock Enkeis).

colo_evo

iTrader: (5)

I think i remember a formula from physics class and it went something like: energy=(linear velocity at the edge of the cylinder)(mass)(radius^2), this is for a homogenius material(same throughout, which is not a rim is not) we went over how to calculate the energy of a non-homogenius cylinder(like a rim/tire)... but it was very complicated and i sold my book back... ill try and find some info on this because it is a very interesting topic.

so, the radius affects the energy at a non-linear rate. this gives you a rough idea. i think if you had a rim that is 2-3lbs less than a stock rim and 1inch bigger it would take the same ammount of energy to accelerate it.

hope this helps.