I was doing a little research today on the effects of tire wear vs tire weight and found that the tread from new to scrap is approx. 20% of a radial passenger tires weight. So if you have a new 25lb tire, then the scrap tire would weigh 20ish lbs. Based on the article I read I'm not sure if they consider scrap to be 2/32" or 0/32", but either way the weight savings is not insignificant.

To make the math easy, if you have a 25lb tire and it has 10*/32" of tread depth, then multiple 25lbs x .80 = 20lbs scrap, subtract the difference which is 5lbs, and divide that by the starting tread depth (10*), you get .5lbs per 1/32" of tread.

I realize this is not overly significant on a newer tire, but using the numbers above with say 3/32" left on your tires you'd be saving 3.5lbs per corner or 14lbs total of rotational mass.

I've read quite a few different threads on why people who get new tires lose mpg's, even sometimes being LRR, but I didn't see too much discussed on the weight differences of new vs old tires.

I have two set's of wheels and tires at home and a third set of just tires and was able to calculate all of the tire's 1/32" weights and came up with between .4lbs-.5lbs per 1/32" for the three tires respectively.

I realize there are a number of factors that go into losing mpg's with new tires, but this is just one more thing to consider. I personally noticed a difference in the driving dynamics of the car while hypermiling when I did weight reductions that varied from 120lbs to 165lbs depending on if I had the spare tire, jack,etc.. The 10lbs per corner in wheel and tire weight reduction was specifically noticeable. It's not that I think my car had just gained 100hp, but while feathering the pedal ever so slightly I was able to maintain higher mpg's with less effort. If this has been discussed and I missed it, apologies.

http://infohouse.p2ric.org/ref/11/10...intro/tire.htm