lighter weight wheels

[jjMustang]

Talking about the weight of the wheel, I read about the valve stem caps on a Bugatti Veyron in an article from PopularMechanics, and I thought I'd share it here:

"Even at 261 mph the wheel and tire has to withstand extreme forces. The valve cap on each wheel weighs 2.5 grams, but it equates to 16 pounds at 261 mph. As the speed moves even higher, the loads increase exponentially. Wallace says at the moment, there is no tire that can withstand the g-loading at 300 mph, but he predicts Michelin engineers will sign off on a top speed with the current production tire slightly north of 280 mph. Perhaps a future version of this car will be engineered to hit that magic 300 mph milestone."

It's interesting how very little weight can result in such greater loads at speed. A savings of nine pounds might improve highway driving more than city driving. I'm going to keep an eye out for such studies now.

[LDB]

That is very interesting.

[trollbait]

Weight differences have more effect in stop and go traffic. There are energy loses in accelerating and decelerating. Then there is a second hit in wheel weight for being unsprung weight, and third because there are additional loses to start and stop their spinning.

[ChewChewTrain]

On my '89 Civic hatchback, I changed my 16 lb. steel rims for 9.7 Honda VX wheels. Did NOT notice any measurable difference in MPG.

Read somewhere that lighter wheels offer the biggest MPG advantage in city driving due to constant reacceleration at stop lights. But if you're driving properly as a hypermiler, you seldom come to a complete stop at intersections, as you approach distant red lights slowly as to hit the intersection rolling when the light is green.

From my experience, lighter wheels are over-rated. Driving-style offers the greatest MPG kick at the least expense. Pumping up the tires to maximum rated pressure is the ONLY mechanical change I make to my car and and I get 50-ish MPG.