I am nearly complete on the restoration of my '68 and am ready to order wheels and tires but need to make some decisions on wheel and tire size first, especially in the front!
This is the set up I have. I have a Hotchkiss TVS suspension on it which has the 2 inch lowering springs in the front and 1 1/2 lowering leaf springs in the back. Also, the heavier front sway bar in the front and now a sway bar in the back too. I have Koni Classic shocks all the way around. If it matters, I have factory power steering. The box was rebuilt by Lee Power Steering and converted to the 12.7 to 1 ratio.
I have had my heart set on Torq Thrust D or similar wheels forever and ever and I would be running a 15x7. In the actual Torq Thrust D, that size only comes in a 3 3/4 back spacing. I would like to get as much tire width in the front as I can but with the 2 inch lowering springs and the 3 3/4 inch back spacing, that really limits me on tire width. After some rough experimenting, I'm making a half-educated guess at a 205 width maximum. I wouldn't consider changing to another style wheel to get more tire width. The Torq Trust D style is the look I want. It doesn't have to be actual Torq Thrust D but would have to be something that looks very similar to it.
That being said, another wheel choice would be the ET Wheels Classic V wheel, which in their 15x7 size, is available in different back spacings up to 4 1/2 inches. I would consider this wheel as it is very similar to the Torq Thrust D.
So my big question is.....does increasing the backspacing and moving the tires inward negatively affect handling?
The reason I ask this is that many years ago, I was running Goodyear GT Radials on Crager 14x7 slotted alloy mags. I don't recall the back spacing of them but assume it probably around 3 3/4. The car handled very well with this set up but I was having tire rubbing issues in the front going over bumps. So I switched to Goodyear Eagle GT's on 15x7 steel wheels with 4 7/16 back spacing. At that time, the Eagle GT had replaced the GT Radial as Goodyear's performance tire. My tire rubbing issues went away but the car did not handle as well with this set up. Within a 1/4 mile of leaving the tire shop, I knew something was different. The steering was not as crisp. It was looser and sloppier.
So I always wondered if the reason for that was because of the change in backspacing and moving the tires inward. I see suspension geometry diagrams which show lines intersecting at the center of the tire contact patch. Do you screw up the geometry, and in turn the handling by moving the tire center contact patch inwards and putting it not where the geometry design intended it to be?
So as far as handling is concerned, would I better off with the 3 3/4 backspacing and a narrower tire or the 4 1/2 back spacing with a wider tire?
Thanks for any thoughts on this in advance.
Dave
