Will G60's and H60's fit under the fenders on a 1970 corvette

Yes with careful modifications. The emergency brake line rides on the outside of the frame, and the bracket holding it may rub on the inside of the rear tire. The 60 series tire is taller than the 50 series and not as wide. I put G50s on the front of my 69 Corvette and H50s on the rear. I had to flare the rear fenders to keep from hitting the fiberglass, and shave the inside of the front fender lips so the front tire would clear. There is a 68 Corvette that has the 60 series tires on, and it fits up into the fender wells. You might need to keeep track of the off set of the rims if you go with a wider rim, (recommended) as to how far out the tire is pushed. The front tires rubbed a little when full turning and a dip in the road caused the tire to ride up so the car could not be lowered at all. I did lower the rear a slight bit as the 50 series tires left a huge gap between the top of the fender opening and the tire. The 60s should fill the fender well. I used the L88 factory flairs but had them cut to jut fit over the tires. For years I used BFG and they worked great. I needed new tires for a car show and BFG was not available so I went with Hancook tires. They not only fit better, they rode smoother, had better traction and handled over all a lot better. It is a slight softer tire so better grip, less jolting on bumpy roads, and handles better on curved roads at above speed limit speeds.

I have the origional American Racing Aluminum 200S (coke bottle) rims with an 8 1/2" width.

Side view.