Well?

 

but they're bouncy

 

ok enuf joking. wtf are you asking for?

You doing some land speed runs in the s2k?

 

lol no I was just curious, my car seems to be somewhat hard to roll around on level ground. I read that tread depth and sidewall size can play a large role so I guess that answers some of the reason why. I was also curious if rim size had an effect once rolling, how can you say when is too big? Generally I've seen 17's and heard 17's to be the best size but is there any technical background behind that assumption?

Aerodynamically Cd what would be a good choice for a bumper? I heard the AP2 front is an improvement. Is it actually worth worrying about?

 

What you're describing is a result of a) toe and b) tread width/contact patch. Try rolling the car by pushing or rolling from the top of the tire itself and not the bumper.

 

wheel size doesn't make any difference but wider tires will definitely add resistance. It's a trade-off between cornering speed and top-end. On a tight track you will be faster with wider tires and on a track with long straights you may be giving back as much as you gain.

 

Wheel diameter makes a significant difference in rolling resistance, just look at all the testing on mtb bike wheels with 24 vs 26 vs 29. But we are constrained by wheel well limitations. Just run stocks.

 

Added resistance could also be a sign of: the brake pads dragging, problems with the wheel bearings, the vehicle is in gear, the parking brake is applied, or a/the tire(s) are under-inflated.

 

MTB test http://www.cyclingnews.com/tech.php?id=tec...s/29invs26inpt1



So if all this is true, why does it seem that 17's do better on the track, even Honda went to 17's, of course wider would be better in the corners, but is the difference not large enough for us to notice? How can you say whats too small and whats too large? Pros and cons to both sides I guess.

 

what makes you think rolling resistance (unless you have the e-brake on) has any significant affect on lap times? Hence the joke on spare tires. You can have very little rolling resistance w/ tiny tires, but your lap times on a course w/ turns in gonna be VERY slow. If you're going for landspeed runs then you care about drag and rolling resistance.

I knew this question was the reason for the thread.

BTW They're talking about total diameter, not the diameter of the wheel.

-Ry