If so, how much?

 

depends on the tire and sidewall profile. I switched to 20's and didnt notice a harsher ride. Depending on the weight of the the wheels you might want to increase your shock dampening, but only if you're ****.

 

Not that big of a deal if you at least stay with a decent sidewall. 295/40/20, 275/45/20, 305/45/20. Also depends if you are lowered at all.
Jeff

 

Also, I believe, if you go with a higher sidewall and end up with a larger total circumference, you will be altering thhe final drive ratio
for the worse. Theres a chart somewhere that shows how much. My guestimate is that the 305/45 may bring you down to around 327, which you would definately feel. You also would have to recal. your speedo. You could of course put in some 410's and end up where you started.

 

I have BFG 295/40-20 runflats. They definitely have a harsher ride due to the incredibly stiff sidewalls. But the handling is crisp and the grip is good, which more than makes up for any added harshness. And you can leave the spare behind.

 

I have 20" KMC Thunders (pretty heavy) w/ Goodyear HP 295/40/20 and did not notice much ride difference. The overall tire diameter is ~1" larger than the 18" F1s which is about a 3% difference on your speedo. I did notice HP loss @ the rear wheels w/ the heavier wheels though.

Buth they look great!

 

I have always liked those, good taste man