What is track width increase worth?

[mbuskuhl]

Suppose you increased track width 2" by changing the offset/backspace of the wheel, how much would that lower your lap time on a 2:00 minute lap? 1/10th? 1 second? Other?

 

For this example, assume tire width remains the same, unsprung weight stays the same (you increase track width with a different offset wheel weighing the same rather than spacers), and track width goes from 60" to 62" or similar on a production race car.

 

All opinions welcome. Keep in mind you might have to increase the fender size to accommodate the new track width so this would effect aerodynamics.

[nape]

From what I've used track width for, it's more of a tuning tool. The wider the track width, it effectively softens the springs and narrower firms them up.

 

There's more too it, but in the realm of club racing on the average budget, that's what I've been able to do with it.

[Driver]

The physics agrees with width=cornering stability=grip. It will effect your perceived spring rate and dampening... but really, all you care about is keeping the rubber attached to the track surface, comfort be damned.

 

Aero: You're looking at more frontal area, and a 27" tire sticking an extra inch out either side is 54 more square inches of it. Keep your fender transitions smooth and you can significantly cut down on the drag. The front wheels are generally in a low-pressure area anyways; the air coming around the nose is spitting vortices around the wheel, your boundry layer is so buggered up there that the added tire may not make any difference.

I'd still sacrifice 3mph on a straightway to pick up 10 in a corner and some later braking. I'd do this with a wider wheel/tire, though, not just spacers.

 

I'm a beleiver in wider track = better cornering, because that's seemingly the only perfomance advantage my car has; a 6ft wide track... and an IRS, that's nice, too.

http://img19.imageshack.us/img19/9995/rimss.jpg

 

I don't like to get into "faster than..." based only on HPDE drives, and only have stop-watch lap times at M-O and Putnam, no Xponder or traqmate data. I will say that, even with street tires, I never got caught and passed unless I was taking it easy on the car... and there were some impressive cars out there on R compounds.