Just switched from using Sport rims on my Itali, for looks, to tuner wheels and the difference is intangible.
As covered in PeeCarNoo's video about which tyres are best (if you haven't seen it I recommend watching it) it is as if you have the offroads bump handling ability without the big compromise on looks. I also noticed as explained in the his video, the way the car now grips more and can turn into corners harder without losing traction is second to none.
I have been testing this all morning around Broughy's track "Cutting Corners" and although I'm not the fastest I have noticed a significant difference of around 1.5 too 2 seconds difference. Also going over bumps, as mentioned, the car will remain flat which is invaluable in a racing environment.
My overall thought on this is if anyone is unsure or doesn't like the look of offroad tyres I do recommend trying to find some tuners that fit and testing around 10 laps (at least) or more each, you can see the results for yourself.
I know this will be common knowledge to most of you but this is for the noobs like me.
on the plus side I'm now at 5 posts on this forum;)
I've heard about the tires thing long ago but I'm just a sucker for cosmetics. Tuner rims are good on street cars or tuner cars, but I still run low profile tires on high end sports and supers just for the looks.
I put tuner wheels on Futo, Sultan, vehicles like that.
But hey I'm not that serious about racing anyway, I race a nice bit, but only for fun. I'm not worried about squeezing every possible fraction of a second from a lap. Especially since me and my buddy most plays in random sessions anyway where most the time catchup is on and you have to avoid people trying hit you. So why bother anyway.