wheel weight vs. wheel size.
- Thread starter StephenB
- Start date
As long as you can get the widths, offsets, and tire sizes that you want/need, the only wheel diameter you *need* is enough to clear the brakes, suspension components, and body parts.
In other words, a larger wheel diameter, in and of itself, is not faster, and in may ways may even be slower.
GA
In other words, a larger wheel diameter, in and of itself, is not faster, and in may ways may even be slower.
GA
erlrich
Super Moderator
If you're talking ITR the class, then you're stuck with 17" wheels - unless you're building an RX8, in which case you can use the factory 18" wheels. Generally speaking however, I've always thought that lighter was always better when it comes to wheels, as long as the tire size you want to run are available for that size rim.
lateapex911
Super Moderator
Larger diameter tires can give you a larger contact patch fore and aft.
But they reduce torque, so you must gear for that. Now, you can often get tires that are lower profile that keep the outer diameter, but allow larger wheels. With street tires, this can be good, as the shorter sidewalls can be more responsive, but race tires are constructed differently, so that's not always a benefit.
But larger diameter wheels and tires can add rotating mass which is hard to spin up and down, so it can hurt accel and braking. Of course, the tires and wheels must be combined to know what you have.
If the overall package is heavier the extra weight is unsprung, so that's bad...worset han if it were equal amounts of ballast. So it's a tradeoff. If you have lots of power and lots of unlimited braking capability, it can be worth it, but generally it's not a 'given' that larger is bigger. In lower hp cars, it's usually not better.
But they reduce torque, so you must gear for that. Now, you can often get tires that are lower profile that keep the outer diameter, but allow larger wheels. With street tires, this can be good, as the shorter sidewalls can be more responsive, but race tires are constructed differently, so that's not always a benefit.
But larger diameter wheels and tires can add rotating mass which is hard to spin up and down, so it can hurt accel and braking. Of course, the tires and wheels must be combined to know what you have.
If the overall package is heavier the extra weight is unsprung, so that's bad...worset han if it were equal amounts of ballast. So it's a tradeoff. If you have lots of power and lots of unlimited braking capability, it can be worth it, but generally it's not a 'given' that larger is bigger. In lower hp cars, it's usually not better.
philstireservice
New member
I would go with the lightest wheel you can find in your price range. Of course tire price and availablity is a factor.
just another bit of info:
Full tread 205/50R15 RA-1 - 20lbs
4/32nd shaved RA-1 - 18lbs
2/32nd shaved RA-1 - 16lbs
205/50R15 Hoosier DOT Wet - 17lbs
225/45R15 Hoosier R6 - 19lbs
245/40R17 Hoosier R6 - 22lbs
for every 1 lb you save in wheel weight it is like taking 20lbs out of the car.....goes for tire weight also
example 1lb each wheel x 4 = 80lbs
just another bit of info:
Full tread 205/50R15 RA-1 - 20lbs
4/32nd shaved RA-1 - 18lbs
2/32nd shaved RA-1 - 16lbs
205/50R15 Hoosier DOT Wet - 17lbs
225/45R15 Hoosier R6 - 19lbs
245/40R17 Hoosier R6 - 22lbs
for every 1 lb you save in wheel weight it is like taking 20lbs out of the car.....goes for tire weight also
example 1lb each wheel x 4 = 80lbs
Larger diameter tires will change the gearing, but will have zero affect on torque.
lateapex911
Super Moderator
yea, of course, I typed that too fast. But it hurts torque multiplication unless countered with gearing. (However, that can be useful at certain tracks with certain cars)
Gary L
New member
Well now, wait a minute...
If you don't compensate for the larger diameter tires by changing some other gearing component, you will shift the entire torque curve to a higher ground speed. Therefore, to say it there is zero effect is not entirely true, IMO.
Flyinglizard
New member
Smaller OD, goes fastest with these little cars. Up to about 400hp. Do a search and you'l find back to back test. I have raced the same car with many diff OD wheels. Smaller has alway been faster. Polar moment, leverage,inertia, yada yada.. I'll put cash on it.
MM
MM
StephenB
New member
Ben, or anyone else...
Are we allowed to run 16" rims in ITR if it only lists a 17 on the spec line?
Stephen
erlrich
Super Moderator
"Cars originally equipped with twelve (12) inch wheels may fit thirteen (13) inch wheels. Cars originally equipped with metric 365 wheels may fit fourteen (14) inch wheels, and cars originally equipped with metric 390 wheels may fit fifteen (15) inch wheels. The above-mentioned cars as well as those cars originally equipped with thirteen (13) inch or fourteen (14) inch wheels may fit up to a fifteen (15) inch wheel. Cars may not fit wheel diameters smaller than those listed on their spec line. All other cars shall retain the wheel diameter fitted as original equipment for their make, model, and type. Knockoff/quickchange type wheels are prohibited. Wheels must be made of metal. Cars classified in ITR may utilize any wheel diameter up to 17” or retain their stock diameter wheels if larger."
Kind of contradictory, but I read that as saying ITR cars can use any diameter wheel up to 17", or their stock wheels if larger.