Alignment changes from bias-ply to radial tires

[evanwebb]

Hey, my dad has a 1968 Corvette and the alignment is all messed up. I'm trying to figure out what to set it to but the original shop manual has alignment specs for the original skinny bias-ply tires. So, now it has 255 width radials on 8" wheels, and it turns not too bad but has almost no return-to-center force, and that makes me think that there is not enough positive caster. I don't know what the actual alignment is on the car at the moment though...

The stock alignment specs are for positive 1 deg of caster, positive 0.75 deg of camber, and 1/4 inch of toe-in. Which sounds like a mess to my race car mind of course...

Are there any ballpark adjustments going from bias-ply to radial tires that someone can give me a reference for?

Otherwise I'll just take it to the alugnment shop and put a mild performance alignment on it, like maybe 4 degrees of positive caster, 0.25 deg negative camber, and 1/16" to 1/8" toe-in?

Suspension gurus please give some ideas, thanks! :)

[joeg]

I'm not a suspension Guru, but I did spend the night at a Holiday Inn Express...

Just attend to the toe, and the car will be a lot better.

[T Broring]

Evan, have you looked up the alignment specs for 74-80 Corvettes (guessing on this range of years). I would think these all came with factory radials and the same basic suspension layout as the 68. Also, I would try contacting one of the big Corvette parts suppliers. I'm sure they would share their preferred specs.
Good luck!

[JamesB]

I would call some of the local corvette shops. There are a few in Maryland and Virginia that might be able to give you the specs.