17" vs 18"
 

thinking of upgrading to 18 inch rims on my brz. Other than looks what are gonna be the main differences between the two?

Cons of 18": Weight, cost of tires, ride quality.

Pro's of 18": Less sidewall movement, looks

Protip: Go on tire rack, use the tire search, and act like you are putting in to get a staggered setup for a car. Do one pair in our 215/45-17 size and one pair in an 18" size of your choice. Complete search. Observe how much more some tire models are in the 18" versions.

Don't forget to account for long term tire costs. You could potentially pay much more for a certain model in 18", or price may end up precluding you from desirable tire models you might have otherwise afforded were you shopping for 17". 215/45-17 is often a hard size to beat for value.

Also note that a 17" wheel that weighs [say] 18 lbs. will have less rotational inertia than an 18" wheel that also weighs 18 lbs. That is because the barrel (where most of a wheel's weight is concentrated) is half an inch closer to the hub in a 17" wheel compared to an 18" wheel.

There is a common misconception that an 18" wheel setup fills out the wheel well better then a 17" setup. If you keep the circumference (or height) the same to maintain the stock gearing and speedometer reading, then the outer measurements are the same.

I agree that if the circumference is the same this is true, but most people who go with 18" wheels go with 225/40/18 thru 255/40/18 tires. Even the 18" TRD wheel setup went with 225/40/18 tires.

225/40/18 has a slightly higher ride hide compared to the OEM 215/45/17 size filling in the wheelwell a little more. There are some people who choose to go with 225/35/18 (which is a tiny bit closer to stock) but that is actually lower than the stock height and will actually leave a larger gap. I think most people avoid the 35 profile tires cause ride quality will suffer even more plus the tires get even more expensive.

I completely understand, but you can achieve the very same effect - even with a 17" wheel.

A 245/40-18 tire has a height of 25.7 inches. A 245/45-17 also has a height of 25.7 inches. Both tires fill the wheel well the same but the 17" has about 1/2 more sidewall height.

But the 18's weigh more (same design/model) and the tires weigh and cost more.

so the ride quality will decrease with sighted a?

all other things being equal, yes.

dont understand what youre trying to tell me...

Takes more to stop the 18's and more to get them spinning basically. Extremely simplified version there.

so an 18 inch wheel would be slower?

i would only go 18" if you're using a turbo, like myself..i need a bigger/wider tire. i break traction pretty easy with nitto motivo's when i romp on them..in the wet taking a turn, have to keep it steady or back end comes out.

if you're not pushing alot of power and want steering response and all then then stick with 17" but looks and power got 18"

I'm planning on doing intake exhaust headers and tune. Dont plan on dropping the car. What do you guys think?