dubga

iTrader: (8)

I know everyone talks a lot about the need for lightweight wheels, and worry about what effect a larger wheel or tire will have on their performance. Car & Driver magazine did a test of this a few months back. I picked up a copy at an airport during a long layover at the time, and have lately been wishing I had saved it. Well, it turns out it is now available online.

They took a Volkswagen Golf and tried upsizing wheels/tires on it. They used the same wheel and tire brand/style and went from a 15x6 in 1" steps up in diameter, to a 19x8.5 wheel. Tire/wheel weight went from 40 lbs to 54 lbs each!! The car's 0-60 went from 7.6 to 7.9, but qtr mile went from 15.9 to 16.1.

I looked up the car and it is a straight-5 with about 170 lb/ft of torque. I really expected a 14 lb/corner increase in weight to have a bigger effect than that on a low-torque 5-banger. I wish they had done the same test with some good ole V8 grunt.

Link To Article

Saturn5

That's a significant difference. A rule of thumb is for every 100lbs of weight changes your 1/4 time by about 0.1 sec. That's sprung weight, like ballast in your trunk, but in the case of wheels, a 56 lb increase cost *2* tenths of a second. Every pound increase in your wheels/tires is the equivalent of about 4 lbs of weight elsewhere on the car.

dubga

iTrader: (8)

I know all that. And .2 seconds in the qtr mile is definitely significant.

My point is that it took 56 extra pounds of wheels/tires to take .2 off the time on a car with half the torque of most fbodies. I would like to see the same type of test done on a 300+ torque car to see how well the "rule of thumb" applies. Especially a car with low-end v8 grunt.

JD_AMG

I think you are missing a big point here. People often say that larger wheels hurt performance on our cars because of traction with smaller side walled/stiffer tires, not just weight. The underpowered golf here obviously shouldn't have any traction issues regardless so you are just seeing the effect of weight.

dubga

iTrader: (8)

I'm not missing a point...I guess I'm not getting mine across. Weight is exactly what I'm talking about. Tire sidewall and grip is a completely different topic. The C&D test just happened to be testing upsized wheels with lower profile tires. The weight difference was my only interest.

There is just as much discussion around here about wheel weight affecting performance. A lot of people look down on cast wheels because they are heavier than the same sized forged wheel because of the performance hit. I would be interested in seeing if the difference on these cars is as great as some think.

I'm not talking about people who are running 12 lb 15 in. racing wheels who are looking to squeeze every .01 second they can get. I'm thinking more of the occasional weekend racers who pass up a set of...say 17 in OE wheels that cost $500 and weigh 25 lbs each for a set of 17 in forged wheels that cost $2500 and weigh 18 lbs each.

JD_AMG

If thats the case then your right, the difference in acceleration will probably be not all that noticeable.
I see what you are saying now, and I doubt the difference in acceleration would be that bad, but braking and handling would likely be a different story.

[Firehawk]-[#530]

iTrader: (1)

I think the unsprung weight will have an effect on acceleration... Just my two cents.