interesting. i assume that we all try to keep the overall dia of our wheels the same irregardless of rim size.for street purposes. if i interrept this right :if we had a very small overall dia wheel there would be more torgue required so our revs would need to go up keeping us in the sweet spot of the motor's torque curve. if we have a very large overall dia wheel then we are cruising? not sure if this compares but the change in dia of a dragsters slicks going from a stop to wheel spin.

 

[quote name='xviper' date='Feb 7 2005, 10:44 AM']

All kidding aside, for those with "street cars", wheel size and weight is not an issue.

 

Vlad, I think your car would look great with bronze wheels, polished lip, dished in the rear... 18's or 19's.

This is purely from a "looks" standpoint.

-SSR Competition
-Volk GT-U
-Volk TE37

 

No.

The larger the wheel diameter, or the larger the outside diameter on the tires, the more torque required to spin up the wheel/tire, leaving less torque for forward acceleration. The smaller the wheel diameter, or the smaller the outside diameter of the tires, the less torque required to spin up the wheel/tire, leaving more torque for forward acceleration.

However, if the outside diameter of the tire is smaller, the engine has to be going faster to get the same forward speed (everything else being equal).

 

i guess that explains why go karts have such small tires and engines that scream.

 

Excellente! More along the figures I originally believed without an actual formula.

I know that in the real world, my brother went from (roughly) 24 lb wheels on his Mazda 3, to SSR Competitions (basically one of the lightest wheels available, 12.7 lbs in a 17 x 7.5)... and his car is noticeably quicker now. His savings was about 14 lbs per wheel/tire (he also went with Toyo T1-S' - a very light tire compared to most)... so 14 x 4 x 10 (if the difference is 10 times... I thought it was less, 6 to 8?)... it's like he dropped 560 lbs in static weight... (336 lbs if it were 6 times).

Another way to look at it might be imagining that you have a full tank of gas and a 250 lb passanger... as opposed to having 10 litres in the tank and you're by yourself. Quite a difference there.

 

Nice choice. Also take a look at the SSR GT-2, they are similiar and lighter. An 18x8 GT-2 weighs just over 16 pounds and the 18x9 about a pound more. Tirerack is currently out of the rears (18x9).

 

I think you may have this backwards. We must ask ourselves which puts more weight further away from the center of the wheel:
-a smaller diameter wheel with a higher aspect ratio tire to make for the same overall diameter?
-or a larger diameter wheel with a lower aspect ratio tire?
I'm going to guess that metal is heavier than rubber, so a larger wheels puts more of it's weight further away from the axle. We all know that it's easier to spin faster if we can concentrate the weight close to the center. Example being a figure skater. If he/she goes into a spin with arms out, without inputting any more energy, if he/she pulls his arms tightly against his body, the spin increases dramatically. All I'm saying, is that it takes more energy (force or HP, if you like) to spin a bigger wheel fast. Now, the big question that hasn't quite been answered:
Which takes more HP to spin - a) A smaller, but heavier wheel? or b) a larger but lighter wheel that has more of its mass further out from center?

ps. We must make the condition that the wheel/tire diameter remains unchanged so that speedo compensation is not required.

 

Einstein must be rolling in his grave.

 

I would still assume that the lighter, larger diameter wheel would be easier to spin. Even if you're comparing a 16 inch 20 lb wheel to an 18 inch 16 lb wheel, most of the weight in either wheel is found in the section which the tire is mounted to (look at the increase in weight even with a CE28N going from a 7.5 inch width to 9 inch width)...

The figure skater could have had a turkey dinner before her competition...

edit - volk ce28n 17 x 7.5 = 13.8 lbs - 17 x 9 = 14.8 lbs