Difference between 15" rims and 17's
Registered User
Joined: Nov 2000
Posts: 2,734
From: Kansas City suburb of
If overall tire diameter stays the same and weight stays the same then there will be little difference.
The reason to go to 15s would be weight and traction to an extent cause the taller sidewall (keeping the same tire diameter) should give you better traction.
Basically, 15s are lighter (racing wheels, bogart, weld,etc) and you can run a taller sidewall so you get better traction.
Hard to say what made how much difference, skinnies up front will help and the traction out back will help, I would say 2 to 3 tenths.
Just guessing though.
The reason to go to 15s would be weight and traction to an extent cause the taller sidewall (keeping the same tire diameter) should give you better traction.
Basically, 15s are lighter (racing wheels, bogart, weld,etc) and you can run a taller sidewall so you get better traction.
Hard to say what made how much difference, skinnies up front will help and the traction out back will help, I would say 2 to 3 tenths.
Just guessing though.
Registered User
Joined: Apr 2001
Posts: 971
From: Colorado
When I went from stock shooters with 245/50-16 rubber to 17x9.5s with 275/40-17 rubber, I noticed a difference in the car, not to mention I weighed the 17x9s and there was a fairly significant ( considering it is unsprung rotating mass) difference in weight.
Registered User
Joined: Oct 2002
Posts: 2,931
From: Upstate NY
A typical 15 inch wheel and tire, even with the same diameter as a 17 combo has less rotating inertia, the resistance to being accelerated or spun up. It may also weigh a little less. Larger wheels with lower section tires tend to concentrate the mass farther from center which increases rotating inertia. I often wonder how the little ricer cars with 19 inch wheels can safely pass in traffic.
The engine not only has to accelerate the mass of the car, but it has to spin the wheels/tires up to speed also, as well as all the drivetrain parts.
Plagerizing from Herb Adam's book Chassis Engineering:
Just removing 16 lbs from the body/chassis would have a very small effect in et and mph. Removing 4 lbs from each wheel and tire would have about 3 times the gain, and removing the 16 lbs from things turning at engine speed would have perhaps 15 times the gain as just removing the weight. In other words, if 16 lbs. from the body equated to a 2 hp. gain, removing it from the wheels would equal a 6 hp gain, and removing it from the rotating parts at engine rpm would be an equivalent 32 hp gain during maximum acceleration.
When lookin for 1/4 mile time differences, you should compare rotating inertia, not just weights, and you should run back-to-back on the same day. The faster the car, the bigger the difference.
The engine not only has to accelerate the mass of the car, but it has to spin the wheels/tires up to speed also, as well as all the drivetrain parts.
Plagerizing from Herb Adam's book Chassis Engineering:
Just removing 16 lbs from the body/chassis would have a very small effect in et and mph. Removing 4 lbs from each wheel and tire would have about 3 times the gain, and removing the 16 lbs from things turning at engine speed would have perhaps 15 times the gain as just removing the weight. In other words, if 16 lbs. from the body equated to a 2 hp. gain, removing it from the wheels would equal a 6 hp gain, and removing it from the rotating parts at engine rpm would be an equivalent 32 hp gain during maximum acceleration.
When lookin for 1/4 mile time differences, you should compare rotating inertia, not just weights, and you should run back-to-back on the same day. The faster the car, the bigger the difference.
Registered User
Joined: Apr 2000
Posts: 1,208
From: Tulsa
Originally posted by OldSStroker
A typical 15 inch wheel and tire, even with the same diameter as a 17 combo has less rotating inertia, the resistance to being accelerated or spun up. It may also weigh a little less. Larger wheels with lower section tires tend to concentrate the mass farther from center which increases rotating inertia. I often wonder how the little ricer cars with 19 inch wheels can safely pass in traffic.
The engine not only has to accelerate the mass of the car, but it has to spin the wheels/tires up to speed also, as well as all the drivetrain parts.
Plagerizing from Herb Adam's book Chassis Engineering:
Just removing 16 lbs from the body/chassis would have a very small effect in et and mph. Removing 4 lbs from each wheel and tire would have about 3 times the gain, and removing the 16 lbs from things turning at engine speed would have perhaps 15 times the gain as just removing the weight. In other words, if 16 lbs. from the body equated to a 2 hp. gain, removing it from the wheels would equal a 6 hp gain, and removing it from the rotating parts at engine rpm would be an equivalent 32 hp gain during maximum acceleration.
When lookin for 1/4 mile time differences, you should compare rotating inertia, not just weights, and you should run back-to-back on the same day. The faster the car, the bigger the difference.
A typical 15 inch wheel and tire, even with the same diameter as a 17 combo has less rotating inertia, the resistance to being accelerated or spun up. It may also weigh a little less. Larger wheels with lower section tires tend to concentrate the mass farther from center which increases rotating inertia. I often wonder how the little ricer cars with 19 inch wheels can safely pass in traffic.
The engine not only has to accelerate the mass of the car, but it has to spin the wheels/tires up to speed also, as well as all the drivetrain parts.
Plagerizing from Herb Adam's book Chassis Engineering:
Just removing 16 lbs from the body/chassis would have a very small effect in et and mph. Removing 4 lbs from each wheel and tire would have about 3 times the gain, and removing the 16 lbs from things turning at engine speed would have perhaps 15 times the gain as just removing the weight. In other words, if 16 lbs. from the body equated to a 2 hp. gain, removing it from the wheels would equal a 6 hp gain, and removing it from the rotating parts at engine rpm would be an equivalent 32 hp gain during maximum acceleration.
When lookin for 1/4 mile time differences, you should compare rotating inertia, not just weights, and you should run back-to-back on the same day. The faster the car, the bigger the difference.
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