So how much power do you really lose with 18"rims compared to some 17"rims?

[TracOwner]

Ok, I can't decide whether to go with 17" or 18" rims. People say "17s for performance 18s for looks" but how much slower would the car be with 18" rims compared to 17"? Is it really a big difference like people claim it is?
I want my car to be both fast and nice looking.

 

[audiodan]

If you get the correct profile rubber doesn't the total diameter of tire equal out?

 

[Cheks_Talon_TSi]

Ok, I can't decide whether to go with 17" or 18" rims. People say "17s for performance 18s for looks" but how much slower would the car be with 18" rims compared to 17"? Is it really a big difference like people claim it is?
I want my car to be both fast and nice looking.

Take a look on this tire calculator: http://www.miata.net/garage/tirecalcold.html
Use it to know how much slow or faster your car will become if you change it... you will need the exact size of tires and rims...

Good luck!

Sergio G.

 

[TracOwner]

So some 18" wheels with 245/40/18 tires would be better (performance wise) than some 17" wheels wrapped in 205/40/17 tires?

If I was to go with the 18" rims and 245/40/18 tires I would be traveling 62mph when the speedo reads 60mhp

And if I was to go with the 17" rims and 205/40/17 tires I would be going 55.8mph when the speed reads 60mph?

So basically it all depends on the tires hah?

 

[leet]

It depends on the weight of the wheel/tire combo.

18's generally weigh more, hence the decrease in performance. The less unsprung weight the better.

 

[tonygst]

Also the fact that a 17" rim would have a shorter revolution than an 18" rim.

The bigger the rotation in the tire (i.e 18") = more power it takes to make it reach a 360 degree spin.

Easiest way to put it yes 18" for looks, but for performance either go with 17" or a 16" rim.

 

[leet]

Also the fact that a 17" rim would have a shorter revolution than an 18" rim.

The bigger the rotation in the tire (i.e 18") = more power it takes to make it reach a 360 degree spin.

Easiest way to put it yes 18" for looks, but for performance either go with 17" or a 16" rim.

Ideally your rotational diameter of your wheel/tire combo should be the same as stock to keep your speedometer accurate. Unless you're talking about the wheel by itself, then yes.

 

[brute]

i'd say stick with those stock rims you got on in your pic... they give it a nice sleeper look

 

[99gst_racer]

Also the fact that a 17" rim would have a shorter revolution than an 18" rim.

No necessarily. The distance of the revolution depends on the total circumference of the wheel/tire combo. So, the circumference depends on the profile of the tires.

For example: A 17" wheel with a 50 profile tire will require 76.3" to make one full revolution.

An 18" wheel with a 35 profile tire will require 73.4" to make one full revolution.

If you want a bigger wheel, then you simply use a smaller profile tire and you can have the same (or very very close to) amount of revolutions as a smaller wheel. IMO, it all comes down to rotational mass (weight of each).

 

[Cheks_Talon_TSi]

No necessarily. The distance of the revolution depends on the total circumference of the wheel/tire combo. So, the circumference depends on the profile of the tires.

For example: A 17" wheel with a 50 profile tire will require 76.3" to make one full revolution.

An 18" wheel with a 35 profile tire will require 73.4" to make one full revolution.

If you want a bigger wheel, then you simply use a smaller profile tire and you can have the same (or very very close to) amount of revolutions as a smaller wheel. IMO, it all comes down to rotational mass (weight of each).

I agree with you... wheel/tire combo is what you have to consider...

Good Luck!

Sergio G.

 

[killakev805]

No necessarily. The distance of the revolution depends on the total circumference of the wheel/tire combo. So, the circumference depends on the profile of the tires.

For example: A 17" wheel with a 50 profile tire will require 76.3" to make one full revolution.

An 18" wheel with a 35 profile tire will require 73.4" to make one full revolution.

If you want a bigger wheel, then you simply use a smaller profile tire and you can have the same (or very very close to) amount of revolutions as a smaller wheel. IMO, it all comes down to rotational mass (weight of each).

That is a factual statement, as far as the circunference of the wheel and tire that is kind of like changing your gearing to give it more top end, or to get off the line quicker.

If you are looking for performance it comes down the the MOI (Moment of Inertia). The MOI is a measurement of rotational mass, but what can confuse people is one set of wheels could actually weight more than another set, but the MOI will be less. The way to achieve that is by making the outer part of the wheel lighter, that reduces the the effort required to move the wheel, and this can affect performance on both straight line, and turning stituations because it requires less effort to turn the wheel. But if you make the outer part too light it won't be as strong, so you have to find the median, so you can be light and strong. Also the bigger the diameter of the wheel the more it will be stressed in the weak spots(like the middle of the spokes), and the more it will stress your suspension components. So, while you are making your decisions on what wheels you need to do like a pros and cons type thing and figure out what your car will be doing in its future. Possibly get some nice 18" wheels for the street, and some 15"-16" for those occasions that require performance.

Just so you know I am not making this up, I engineer and manufacture motorcycle wheels for www.americanmetalworks.com . When your engineering motorcycle wheels the MOI is one of the most important parts.

 

[TracOwner]

thx guys. That helped.

 

[Goodguy162000]

Correct me if I'm wrong, but in addition to unsprung weight and total power it requires to move a larger wheel, I thought that each pound added to your wheels is like adding 8 lb to the car.

 

[killakev805]

Correct me if I'm wrong, but in addition to unsprung weight and total power it requires to move a larger wheel, I thought that each pound added to your wheels is like adding 8 lb to the car.

Your not wrong, but I don't know about the 8lbs. What you are saying is used more as an example, because that is what kind of difference it will make when you can lose some weight in those areas. Like when you put a lighter flywheel on your engine will rev faster.

 

[Thomas91169]

just get rims/tires combo that are as close to the circumfrence as the stockers.

i have 18's with 40's and theyre only a half inch taller than the stockers when i put them side by side. and not that much heavier might i add.

 

[radbradyah]

how much slower would the car be with 18" rims compared to 17"?.

Take into account what kind of driving your going to be doing as well. More rubber is definitely a plus if you're taking tight corners, it also adds some extra comfort knowing you don't have to worry about every pothole in the road. Just something to think about before investing on pricey wheels.

 

[RotaryRyan]

I personally like the way 17's look. I have 17's with 235/45's on them. Also have a 1.5 inch drop. The wheels I have are super light-weight 9lb wheels too

Heres a pic. its not a side view but....

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