Do 18" rims really slow you down?

2002GreyGT · Nov 29, 2005

I have been reading a lot of the forums, and there seems to be a few people saying that putting 18" rims on you car will slow it down because of the rotating weight you are adding.

Does 18" rims really do this even if you keep the propper overall tire/wheel size?

Or is it that people put too big tires on bigger rims and mess up the speedo?

Thanks

~K

AmBo · Nov 29, 2005

I'm sure it slows you down, but not significantly. I remember reading somewhere that it can have something like ~.1-2 off your 1/4. Probably just the weight. I noticed no difference when I went to my 18s though.

Ghost001 · Nov 29, 2005

My dyno guy said that the 18" rims will also give you lower dyno numbers.

bryan0 · Nov 29, 2005

I remember using some online calculator before. 285/35/18's make you car read about 1% slower than it's really going. So if you're doing 101, it'll say 100. Not too big of a difference. Also, at least with my 2000 cobra r wheels, it seems like it would be the same weight if not lighter, since there's less tire. There is only about a cubic inch per spoke being added, so what's heavier? 5ci of wheel or 1" of tire all the way around? I don't know, but it's close.

tomustang · Nov 29, 2005

If the overall diameter of the 18's with a smaller tire wall is equal to the stock 17's it wont be a longer rotating mass

having an extra inch is adding weight over a 17

blackfang · Nov 29, 2005

Many slow you down for the fact they tend to weigh more.

98blackmagic · Nov 29, 2005

More weight and a larger rolling resistance = slower et's

hognutz · Nov 29, 2005

answer is dependant on the wheel wieght and tire size. If you run a lighter than stock forged 18" wheel with the same diameter tire as stock then no.

if you run a 30lb 18 wheel with larger diamerter than stock tire then it can slow you down a bit.

A light 18" rim with the right tire size is going to be very neglegable on hindering the performance. you could even run forged 19" on 30 series tire if you wanted to buy $500 a piece wheels.

All things being equal though a smaller wheel will wiegh less. a forged 17" wheel will be the best choice for the quarter mile. there may even be some 16" wheels that will clear the factory brakes but I am not positive on that. now if you wanted to run some exotic brake setup with 4-6 piston calipures and 14" rotors 18" wheels may be the best choice for auto x.

As for you speedo just keep you same overall diameter and everthing will be the same.

TrueBlue03 · Nov 29, 2005

it probably does slow you down a little tiny bit, but i didnt notice it at all but i dont take mine to the track ever or do much racing at all.

ADRENLN · Nov 29, 2005

it slows you down a bit. like stated above, its not the size....its the weight.

the expensive wheels i bought were actually lighter then stock bullitts despite the 18 in. size. it was the wider tires that added all the weight.

dont forget when people do rims, either 17's or 18's they go from 245 to 275 or maybe 295. that is what adds the weight and will slow you down.

like i said even with 17, when you throw on a huge tire your adding weight.

i weighed my wheels before and after the tires. stock bullits and the 18 in. bbs. trust me the weight is in the tire.

RedBullitt · Nov 29, 2005

yeah its all about the added rotational mass vs your stockers. go with lightweight ones, or else you will feel a difference going from a standstill. dont get me wrong its nothing huge, but its definately there

blackink00 · Nov 29, 2005

with my 18's i cant hit 13's and when i put on my 15" with DR i go down to 13.5 so bigger rims do slow you down. but they do look liek teh win

ponysarepretty · Nov 29, 2005

tomustang said:
If the overall diameter of the 18's with a smaller tire wall is equal to the stock 17's it wont be a longer rotating mass

having an extra inch is adding weight over a 17

A thinner sidewall could slow you down too.

Henceforward · Nov 29, 2005

Search DerekStangGT posts...

He noted that they weighed more.

http://forums.stangnet.com/member.php?u=41427

HoustonGT · Nov 29, 2005

I'm sure they do. Just like someone already said, even if the 18's weight less, the wider tires will make up for it and i believe rotational inertia will actually multiply the affect. So if your new set-up weighs about 7/bs more per tire/wheel, the effect will be greater due to the rotational force.

tomustang · Nov 29, 2005

ponysarepretty said:
A thinner sidewall could slow you down too.

jasonh_86 · Nov 29, 2005

I agree with the weight/sidewall thing.

Bigger wheel/wider tire = more weight..

Shorter sidewall = less sidewall flex..

Less sidewall flex means less traction/grip off the line.. that's why you see all those drag cars with 29" slicks/radials..

If i had a lower gear, i would've used some 15x10" wheels with some 29" DR's on them this past weekend, but it would've slowed me down due to the additional tire height..

DogVomit · Nov 29, 2005

ahhhh, throw in some gears and they'll compensate for area. Look for light 18's and gears and that might work.

GoBabyVroommm · Nov 29, 2005

Yes it does but then again so do my Torque thrusts IIs 17x11. Go with what you like, your paying for it.

mity2 · Nov 29, 2005

Ghost001 said:
My dyno guy said that the 18" rims will also give you lower dyno numbers.

mine told me the samething. But for few hp, I'd pick sex appeal tho

mine is 18", and chrome plated. Might as well be made of depleted Uranium

Do 18" rims really slow you down?

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