Does rotational mass affect non-driven wheels?

[aardvarcus]

Originally Posted by PaleMelanesian

Counterpoint.

If it's a lightweight car with heavy wheels, it can work out to 2%. (my car - 2500 lb, lose 6 lb per wheel) That's in the same ballpark as power increases claimed from air intakes or exhaust mods, BUT it also benefits ride quality, handling and braking.

You can also move to a smaller diameter wheel. That will improve rotational inertia even more, along with usually being lighter due to the smaller size.

This is an upgrade I'm considering, downsize from my heavy 16" alloys to a 15" sport wheel. Stock rims are 17 lb each, Konig Helium 15" are 11 lb and cost under $100 each. I'd love a set of TE37's but the price...

A less expensive option for lightweight wheels is to look for oem wheels off of hybrids with the same lug pattern. My Toyota Celica is now sporting 15" Prius wheels, down from the stock 16" alloys saving over 5lbs a corner.

[PaleMelanesian]

Good idea in most cases.

Unfortunately most recent Honda models are 5-lug while the Fit is 4-lug. Only the rare first gen Insight and Civic hybrid wheels would work, and being rare they're also expensive.

[serialk11r]

Originally Posted by PaleMelanesian

This is an upgrade I'm considering, downsize from my heavy 16" alloys to a 15" sport wheel. Stock rims are 17 lb each, Konig Helium 15" are 11 lb and cost under $100 each. I'd love a set of TE37's but the price...

I didn't know about the Konig Heliums, thanks for mentioning. The stock wheels (cast aluminum) on my car are 15" so they weigh 14lbs front 15lbs rear or something like that, so it wouldn't be much of a reduction considering that the brake system and tire are both well over 20lbs. Those seem like quite good bang for the buck though. Another one to consider might be Kosei K1Rs or K4Rs or something, cheap cast aluminum and light. Only problem is these aftermarket wheels don't tend to come in the sizes that are ideal for skinny tires, they seem to all be 7 inches wide or more when these small and light cars work well with 6 and 6.5".

On Spyderchat some people splurged and went for 15x6.5 Volk CE28N that are 8 pounds flat...I didn't even know wheels under 10lbs existed! Aluminum rotor hats and aluminum brake calipers you can cut unsprung weight another 6 pounds or so, both mods are ~$100/lb unsprung weight reduction, which is certainly cheaper than a lot of weight reduction mods but still a good chunk of money.

[niky]

I've seen those legendary seven pound-ish Spoon wheels. They are unbelievably light.

15x6.5, try ROTA Auto-X, they're cheap and around 11-12 pounds. I just don't know if the off-set will work for your car.

[PaleMelanesian]

Originally Posted by mcrews

BUT not reducing the overall diameter of the tire.
infact please consider increasing the overall diameter of the tire. (many threads on this topic.

Of course. I've got a spreadsheet set up with various sizes and rev/mile for quick reference if/when I do this. A step higher aspect ratio looks good to me, above and beyond the change due to wheel resizing.

[serialk11r]

Originally Posted by niky

I've seen those legendary seven pound-ish Spoon wheels. They are unbelievably light.

15x6.5, try ROTA Auto-X, they're cheap and around 11-12 pounds. I just don't know if the off-set will work for your car.

I don't think they come in 4x100 bolt pattern, and besides why get those when Kosei 15x7s are a hair over 10lbs for barely more money. If I were to replace the wheels I think I'd have to go Enkei RPF-1, lightest cast aluminum wheels out there at a bit over 9lbs. There's a couple of <8 pound wheels but at 3000 bucks a set I'd cry every time a scratch got on the finish, that would be no fun.

[LeanBurn]

Originally Posted by aardvarcus

A less expensive option for lightweight wheels is to look for oem wheels off of hybrids with the same lug pattern. My Toyota Celica is now sporting 15" Prius wheels, down from the stock 16" alloys saving over 5lbs a corner.

I did the same thing with the Corolla. I can sure feel the difference in acceleration, handling and steer-in when I switched from the stock 15" steelies to the 15" Prius wheels.