I think I will be using 18 inch rims and car will be minitubbed of course.

Just want to get you opinion on what will look the best???

what's your engine size and HP?
on what rims? 17 or 18" ?

550 HP & 18 inch rims

It's your checkbook... Why don't you go to a tire dealer and set the two side by side? I'd think that would be the easiest way to make a decision.

What else are you doing to the car? Cage? sub frame connectors? SLP did some studies on ragtops prior to shoeing the first 4th gen SS cars. I know you are talking 1st gen but feel this applies even more to the 1st gen. SLP found that 275/40/17's on all 4 corners would work on a Z28 coupe without redesigning the substructure of the car. The convertible it was decided wouldn't live with the added performance the big 17's so they opted to run 16's and a tire less wide to avoid warrantee issues. They almost restricted t-top 4 gens to the 16's as well!!

The moral to all this is all that tire and power will tear up a coupe let alone your ragtop so you need to beef up the substructure so you don't destroy you investment doing a few hard launches or pushing the g's in the corners...

Yeah Thnaks DJD. I am running welded subframe connectors and a factory X-brace. I'm leanind towards adding a 3/8 peiece of metal on the inside of the frame rail as well as the outter piece to help make up for the frame rail modification needed to run bigger tires. I may even fabricate a cross brace in between the frame rails just under the convertible top motor to hold things together. -C.

rear tires should be in proportion to your front tires. they don`t have to be the same size, but fairly close. so if you run 335`s in the rear, what will you be running in the front? 235`s have a tendancy to rub

The bigger the better, but not so big as to rub.

I would think that if you have the skill to mini-tub a car. Then taking measurements to fit the proper sized tire/wheel, should be an easy task, smile.gif .

I'm pretty set on 245/40/18 in the front. Its not a question of what will fit...I'm just wondering if 335's will be too much for a convertible both visually and structurally conidering it is a convertible with a 469 C.i. motor with 550 HP. -Chris

Well, if you like to weld, get these... weld in SFC (http://www.detroitspeed.com/SubframeConnectors.html)

335s are a very tight fit on 67-68s even with a 3" mini-tub you will need to trim or roll the lip. I did a 2.5" mini-tub with 315s and have plenty of room and they don't look stuffed in there...they just look good. Also you wont have to trim as much frame rail to fit the 315s...this is good if you plan to use leaf springs.

A 245/45/17 or 245/40/18 will fit fine on a 8" wheel with 5" bs and disc brakes.