Learn me: wheel width worth work? Wongue withter

So I'm looking to go from a 205 16, to a 235 or 245. How much advantage is this on say, a 60sec autocross course? Are we talking tenths? Or seconds?

And not slicks. Just 200tw

I'm guessing the title confused a lot of people. 

Depends. Are we running the same tire make/model in both situations? Are the current tires fresh or timed-out? Any gearing change that will require an upshift/downshift?

But, total WAG, I'd expect the wider tires to deliver faster autocross times. 

I'd be expecting seconds myself, especially if you're giving those tires some support with a wide wheel.

In reply to Keith Tanner :

That much? Dang. That makes me feel very good about keeping up with NDs in CS...with my factory 195s. Makes me want to upgrade. 

How about rim width and horsepower numbers?  Oh, the days when a 235 was rollin' hard on a 5.0 (that made like 225 hp) . . .

All else equal (which is pretty unlikely realistically) and a comparable wheel width increase, I'd guess 1s +-.5s per 60. On the same wheels...not zero but close to it.