345s in back? handling?

Definitely more tendency to push.

Dave

 

It will make the car understeer so much more, and the stock car understeers plenty.

360 Modena understeers, the F430 understeers less than the Modena, the Scuderia understeers less than the F430, the Stradale understeers less than the Scuderia.

In the Scuderia I ran a 345, but combined with a 295 front and it did still understeer.

For street driving, you won't notice the difference, because you need to get closer to the limits of the car to feel understeer/oversteer.

 

Honestly I think a 345 is a huge overkill on a 360. It will probably adversely affect handling in several ways.. 1 being turn in, 2 being the stated oversteer, and 3 the already twitchy balance at the limit. It changes the gemometry of the suspension, effectively with adding all that tire on the inside track. You may experience more straight line traction, which really isnt needed, but in the turns you will have a lot more tire to heat up and your grip will be less fluid and consistent, and probably be more nervous at the limit. Turn in and toss-ability will be lost. Money is better spent on lighter wheels (not super wide) and lighter tires with more grip.. Like R888s/Corsas/PS Cups or other DOT-R compound. If you want more grip and handling, change the tire compound, not the size.

What is your real goal with going that wide? Are you really going to be driving at 8 or 9/10ths on the street in the corners? if not, you probably wont notice a difference. You will notice a lot more tram-lining on the freeway over concrete. If you just want to have huge scary aggressive looking rear end, then by all means

 

I'm positive I would not like the change. Your grandmother might not be able to tell. One good truism to always consider: It's pretty hard to outsmart factory engineers.

Dave