Rotating mass can account for approximately an extra 3/4 lb for every pound added. In other words, a pound of rotating mass would be equivalent to about 1.75 pounds that have to be accelerated. Of course there are other parameters to consider such as the wheel/tire’s moment, but I would consider that a good rule of thumb.
Originally posted by GSpeedR
One exception is the Azenis which are just heavy ass tires in any size :tsk:
They’re a little heavy, but not too bad. My current Goodyear Eagle HP’s weigh 18.11 lbs each and my new Azenis are 20.5 lbs. That’s only two pounds heavier, not a big deal at all. I also have the nice and small stock 14" alloys (which are BEAUTIFUL) and 195/60/14 tires.
Tire size vs Power Reduction
I found this info in Honda Tuning Spring 2001.
Test car was a civic dx with aem intake, Hp header and tanabe exhaust.
Stock tire size = 185/70/13
circumference = 6ft 3/8 in
weight = 29 lbs
hp = 113.6
upgrade tire size = 205/40/17
circumference = 6ft 2 1/8 in +1.85in
weight = 38.5lbs +9.5lbs
hp = 109.8 (-3.8hp)
(weight and circumferance are with the tire on the wheel)
On the dyno the car measured 113.6hp, the tires were removed and the aftermarket wheel and tire combo was put on and strapped back on the dyno and sufferd loses throughout the entire rev range, at peak 3.8hp was lost but drops as high a 6 hp were realized at 70mph.
Re: Tire size vs Power Reduction
Originally posted by freeload303
[B]I found this info in Honda Tuning Spring 2001.
Test car was a civic dx with aem intake, Hp header and tanabe exhaust.
Stock tire size = 185/70/13
circumference = 6ft 3/8 in
weight = 29 lbs
hp = 113.6
upgrade tire size = 205/40/17
circumference = 6ft 2 1/8 in +1.85in
weight = 38.5lbs +9.5lbs
hp = 109.8 (-3.8hp)
(weight and circumferance are with the tire on the wheel)
On the dyno the car measured 113.6hp, the tires were removed and the aftermarket wheel and tire combo was put on and strapped back on the dyno and sufferd loses throughout the entire rev range, at peak 3.8hp was lost but drops as high a 6 hp were realized at 70mph. [/B]
Fascinating. What’s interesting is that adding almost 10 lbs (20 for both front wheels) only lost 3.8 horsepower. I woulda thought it would have been more. That’s good stuff, I never thought heavier rims actually lost you horsepower on the dyno…