Tire size for 68 with 4:11's

[sleeper 68]

I think i need a 28 inch tire or better for my 68 since my gears are so low and i have a 455 in it. What are my best options?

[71GS455]

Something in a 275-60-15 should be in that height range. You can do them on 15x7's, but they really would like a little wider rim. Go to tirerack.com and do a search by size and use the 275-60's and see the different brands. You can also click on specs for the resulting tires and see others with similar heights. You could do a 235-70-15, but they won't be nearly as wide as the 275's. However they'll fit better on a 7" wide rim.

[sleeper 68]

My problem is i don't want to run out of rpms in the qaurter, will 275's do that?

[71GS455]

You can play with this calculator:
http://www.ringpinion.com/Calc_RPM.aspx
But I don't know what you run, so I can't tell you if you run out of RPM.
With that height, 4.11's, and ~110 mph, you're looking at about 5600 RPM. That would be a low 12 second/high 11 second car.
For a 105 mph car, you'd be around 5400 RPM. That would be a low 13 second car, maybe into the high 12's.

You may want a taller tire for the track, if you need less RPM's or have a converter that slips on the top end (high stall), which pushes the RPM's even higher. You could go with a 29" tall tire and that would knock a little more down. OR get either an OD transmission or a Gear Vendors overdrive unit added to your current transmission (no cheap).

[sleeper 68]

Do you know if that is the absolute largest tire i can fit under my 68? Thanks for the help so far. i have been working on my car for three years now, i haven't yet ran it down the track i still need to find the right tires and a dive shaft.

[71GS455]

I really don't know what will fit in a 68. The wheel wells are different than the 70-72's. You may be able to do some searching with the link near the top of the page to find out.

[gdbuick]

Sent you a pm with some links from this board.

Later
Greg

[sleeper 68]

Thanks for all of the help i really appriciate it.