I was actually going to PM you. I would think a 215 would still offer decent driving on the street. I’m not building an auto cross car but it isn’t a drag car either. Would that be a fair assumption?
It would, like I said it depends a lot on wheel diameter. For a 15” wheel a 15x7” with 4.25” of backspace would let you run a 215/60/15, possibly a 215/65/15 (26” tall) or a 225/60/15. I ran 225/60/15’s on my Duster on 15x7’s with a 4.25” backspace before I went to 18” rims. There’s decent tire selection in 225/60/15, and the car handled decently with the 1” torsion bars I had in it at the time.
Step up to a 17” and a 245/45/17 is pretty easy too on a 17x8 with 5” to 5.6” of backspace. Lots of great tires in that size too, and it would be a pretty significant improvement in handling, mostly just with better tire compounds and selection. But that’s more rim diameter than some people want.