Affects of using different wheel size?

[MountaineerSTi]

Assuming everything else about the wheel/tire is the same, what difference will there be between a 17" wheel and an 18" wheel? Acceleration? Handling? etc.?

Thanks

[SentraWV]

Theoretically, a smaller wheel should be lighter and take less power to rotate and therefore make the car a bit quicker. It also could effectively change gear ratios and result in quicker acceleration, IIRC. Exactly how much would depend.

And, of course, it will screw up your speedometer.

NP: Liquid Tension Experiment, 2

[gtfour77]

Caleb,
The difference can be miniscule....Some people prefer a nice light 18 inch wheel with a lower profile tires instead of a bit larger 275-40-17 or even 315-35-17.... There are just more choices in the 17 inch tire size...

[SeanB]

Smaller wheel = possibly lighter, less rotating mass, but you can probably hit the rev limiter because of gearing

Larger wheel = heavier, more rotating mass, wider selection of tires, less likely to top out in a gear

A lot of STS guys are running 16s on their Hondas that came with 14s because of better gearing and wider tires.

[Jason V]

The only real way to know which is better is to try both.. and even then the difference may be very very small... For gearing compare the total diameter to stock.. a 17" wheel tire combo may be shorter or taller than an 18" combo... depends on tire size. now does your car need taller or shorter gearing??? good question and the answer is car specific... small, low power, light, FWD cars (think crx, A1 VW Rabbit) tend to need shorter gearing so you see them on wide 13" setups... compared to BMWs that can take very large wheel combos and have a bit more power to overcome any gearing hit and being a tad more in weight they need all that tire!!

IMHO Pick your combo based on what car it is for, tires available, and price...

[MountaineerSTi]

Thanks for all the input.

I was really thinking about a separate set of rims mainly for winter tires but then thought I could swap the winter tires off in the warm weather in favor of some nice stickies in case I want to come play AutoX in a "big" sedan (Legacy GT Spec.B). The stock rims are 18" and it's just expensive to have a separte set of 18" wheels, 18" winter tires, and 18" stickies....

I also need to check and make sure a 17" would clear the brakes (not sure how big they are).

[ShortysTRM]

mmmmm...nice car.

[MountaineerSTi]

OK...so what class would the overpriced sedan be in with the following mods:

Front and Rear Swaybars
Catless Downpipe
Reprogrammed ECU (Cobb Accessport State 2)

[ShortysTRM]

I didn't think a car would be SM legal without a cat, but I don't know that all of the SM guys run cats, so possibly there.

I think you could run STU if you had a high flow cat, but I doubt it without.

I may look further into this, so stand by.

[ShortysTRM]

OK, catless is allowed in SM and SP from what I can tell, but not STU.

[MountaineerSTi]

hmmm....so high flow would allow me to run in STU? you can change boost and such in STU?

Thanks for helping me out.

[ShortysTRM]

I'm not so sure about changes in boost. It may be allowed since it's an ECU change and not a mechanical boost controller, but I'd have to look. We're like 8 minutes from a newscast right now, though, so I have no time.

[MountaineerSTi]

you choose work over these forums?!?

I read through the rules and it sounded like stock boost was to be used in STU but I'm terrible at reading those rulebooks.

I'll probably go catless anyways...then I could use my same SM car magnets! :D

[ShortysTRM]

Just make sure that going catless doesn't make a brand new car smell like arse after a year. I went catless on the Grand Am for a while, but I coudn't take it. I smelled like I'd been mowing the lawn every time I drove it.

[gtfour77]

We miss you in SM Caleb!!! :drive:

[Jason V]

STU is a no boost change class (for now) SM is open on boost.. and whatever SP class the car falls into (not sure B,C,orD SP would be my guess LOL) would allow any boost changes provided the turbo and bypass valve are stock (again read the rules for all details) ecu changes are unlimited in SP classes... SP and SM allow for stickies , your wheel idea is great.. stickies in the summer and winter tires for snow... dedicated autocorss rims may be ideal (ie wider) but this is not Nationals.. we are out here to have fun!!!