Can Form == Function?

[cmj]

I will be running 16x8" wheels.

New: 195/45/16
Old: 185/60/14

I will most likely be running wan-li, or some other hard china compound since these are summer wheels, won't see much lateral G, and don't need to be sticky at all. As far as tire weights, I won't have any good comparisons until I figure out what factory tires weigh versus the new shoes.

[cmj]

Originally Posted by Patrick

Negative camber will probably help your cornering if you corner hard, but your tires will wear out faster on the inside edges.

This is something that I have remedied by flipping tires once every season. I consistently get 30k miles out of a set of wan-li's by flipping them every 10k miles or so. Not ideal.. but it works. I realize some of you cringe at only getting 30k a tire.. But I only pay $30 a tire so I'm not terribly upset.

[Frank Lee]

Additional wear is probably a good indicator of additional friction.

[Patrick]

Originally Posted by cmj

I will be running 16x8" wheels.

New: 195/45/16
Old: 185/60/14

I will most likely be running wan-li, or some other hard china compound since these are summer wheels, won't see much lateral G, and don't need to be sticky at all. As far as tire weights, I won't have any good comparisons until I figure out what factory tires weigh versus the new shoes.

OK, so your OD is about the same, the new wheels are lighter and the new tires may be heavier, the same, or lighter. So your moment of inertia may be slightly better, the same, or slightly worse. You've increased section width by 10mm, but covered some of the frontal area by lowering the car. I predict a slight increase in mileage. Just my humble SWAG at it.

[orange4boy]

Drag from wheels is one of the biggest single drag sources in a car. Widening tires with all other things the same will almost certainly increase your drag. There is one reference in Hucho which shows a .29 to .30 change going from 175-70-15 to 185-65-15.

Lowering a car may or may not increase drag. It depends on the car. Most wind tunnel tests show a reduction in drag with increasing road clearance. Belly pan it and you may offset the increase.

RR seems to be much more compound related than section and width related. The differences in compounds in the tires you choose will have a much greater effect on RR than differences in section.

The rotational mass issue is really trivial AFAIK. It may make a slight difference in acceleration but almost none in FE. Your engine's efficiency in converting heat to kinetic energy will have a much greater effect on FE that how quickly you can convert that energy into velocity. The extra weight will have a small effect on RR but that would be almost unmeasurable. If you are drag racing (or stopping quickly) then it will make a difference.

My two bits.

[RobertSmalls]

Originally Posted by cmj

I will be running 16x8" wheels.

New: 195/45/16
Old: 185/60/14

I will most likely be running wan-li, or some other hard china compound since these are summer wheels, won't see much lateral G, and don't need to be sticky at all. As far as tire weights, I won't have any good comparisons until I figure out what factory tires weigh versus the new shoes.

The Tire Rack lists the mass of almost every tire they sell on the Specs page. Assuming most of a tire's mass is in the belts and tread, the small increase in section width will result in a small increase in mass, and a moderate increase in inertia. It may be too small of an effect to notice, though.