Amx rear gear and tires

[Leadbut]

I’m getting ready to change the rear gear set on my ’69 Amx. It used to be an auto car. Now it has a T-10 in it. But I still have the 3.15 rear gears in it. With 26-inch tires.

It’s a mildly built 390 that I drive on the street with an occasional trip to the track.
I was thinking of putting a 3.54 gear set in it, but then I thought why not put a 3.73 set in it and get a set of 28 inch tires for the street and use my 26’ for the track.
Sounds brilliant.
Will it work?
Can I fit a set of 28-inch tires on the back of the car? What size? (15-inch rims).
Anyone got a better idea with out shelling out $3000 for a gear vendor unit?

Thanks

[AMX69PHATTY]

I've ran 3.73's for about 20 years in my '69 AMX auto with
255/60/15's on the rear, ~27" dia., and 26" slicks at track.
Top speed is ~110mph at 6000 rpm with the slicks at the line.
With the street tires speed is about double the tach.
65 mph is about 3250 rpm's.
It's a little steep, but I don't "travel" in the car and
when needed it jumps from a stop sign / light
28" tires might fit if the rim offset is deep enough.
I have 15x8 Mag 500's with 4-1/2 back spacng
and have more than 1" clearance with the leaf spring.

[theamxguy]

I run 28 inch slicks on the back of my '69 AMX. However, we had to clearance it a bit. It is tightest at the bottom, and a 28 inch slick will grow some at speed, unless its a radial type. I think 27 inches is about all you can go with stock wheelwells. More gear is almost always a plus at the track as long as you can hook! I run 4.30's in my car, but I don't travel far in it.