Is there any difference in performance or mileage in a 21 lb. vs. a 25 lb. tire? reduced weigt in rotating mass can be quite effective such as a lightweight flywheel or wheels. will 4 lb. be noticeable?

 

are you racing? is youre car stripped down? if not dont worry about it. but if you really want to save 4lbs/tire go right ahead. less rotating mass is good, but unless you have some serious weight reduction, 16lbs is nothing. you still have all that sprung weight to carry along with it. youre most likely NOT going to notice the difference in weight savings.

for a more drastic comparison, i was running 19x8.5 and 19x10s that weighed at least 55lbs each with tires. now i dropped down to 16lb 17x9 forged monoblocks with 24lb tires, tipping thee scales around 40lbs. now THAT was a big difference in acceleration... at least a 15lb/corner drop. mileage didnt really change cuz i found myself enjoying the better acceleration... that and my car was pretty gutted at the time.

 

yea i agree... 4lbs in your case shouldnt be noticable

 

Won't make a difference.

 

Dropping 4lbs at the tire is more effective than at the wheel, but on a 40lb+ combo doesn't change much

 

I doubt you'll notice.

 

IIRC, each pound off your tire/wheel combo (rotational mass) is equivalent to 10lbs curb weight.

4lbs (per tire) x 4 = 16 lbs

16 lbs x 10 = 160 lbs taken off the rotational mass.

Hence why lightweight rims are so expensive...