Appropriate Wheel Offset for 18" Wheels?

MuuMuu101 said
I'm curious now... Because I know there are quite a few cars with a 275 series tires and I never here them mention needing offset shackles. I've got to do some research. I autocrossed with Tomswheels and his '67 Valiant and he was running 265/35/18's all the way around (granted he had an 8.8 in it). What about the Red Valiant or the Green Brick? Anybody know about those?

What needs to be modified for the 1/2" shackles because the idea of how they work isn't really connecting in my head. I'm assuming the perches need to be moved in and the offset shackles move them on the frame side, correct? If not, it makes more sense to pay $150 for the kit instead of $250 on tires (just back two). If so, I'll just do a mini-tub years down the line and move the perches then.

Also, the car needs to be on all 4 wheels within the next 2-3 weeks or so (before school starts hence the rush).

There are also a lot of folks with 1/2" offsets, not to mention the 3" spring relocations. You're welcome to try it, but all I can tell you is that on MY '71 Dart there is absolutely no way you can run a 275 without a 1/2" offset. The only Dart's I'm aware of that run 275's have at least a 1/2" offset and a quarter lip trim. That will be especially true for a lowered car. Also, not all of these cars have the same amount of space. Pre-70 Darts are VERY tight out back, most can't even get a 255 without rubbing. So, its entirely possible the early Valiants have more space than a 70-up Dart.

The 1/2" offset moves the front spring hanger over a little more than a 1/2", so that its up against the frame rail in the front. The offset shackles mount in the same place as the stockers, but they're offset a 1/2" to move the rear of the spring over. That places the spring even with the inside of the wheel tub, so you can run as wide of a tire as will fit in the stock wheel tub. The hangers and shackles bolt on, but you need to move the spring perches in 1/2" on each side, so 42" C-C.