I have a line on a new set of 15x7 Torq Thrust II's with 3 1/2" BS that I am considering for my 64 Lark project. Anyone running 15x7 Rally's on their 64/65 Larks? If so, what is the BS on the wheels? ANy info would be greatly appreciated. Thanks, Eric
Offset, and Back Spacing are not the same. 3.5" BS is what they used on the 81-87 Buick Regals. For the 70-72 Skylark GS, 4.25-4.50" BS will work on the 7" and 8" wheels respectively. A 10" wide wheel will like a maximum of 5.625" for the widest tires. The 68-69 likes 5" BS for the 8" wheel I'm not sure about the 64-65, but I wouldn't buy wheels with 3.5" BS. Maybe someone with a 64-65 can add to this. I would hold off for now until you get more information.
Backspacing on the 15x7 Buick wheels is 4-3/8", except for the WG code wheels..... http://www.v8buick.com/showthread.php?t=196455 3.5" backspacing will move the tires out too far. 4.375" works nice, but a little more would be optimum for a 7 inch wide wheel if you want to run fat tires.
You'll need at least 4" of backspacing on a 7" rim (which is actually 8" wide) but 4.5" would be better. I was able to run 16x8 TT's with 4" backspacing but I could not go any wider than 225 tires. When I moved up to 255's I had to go with 5" backspacing.
If you go to a 71-72 Buick 8.5" rear end, you will need more backspace. I don't know the exact width but those rears are about 1" wider, I think. (1/2" per side?) I had my 15" Buick ralley wheels cut and welded with a 1" spacer behind the center and made 8" wheels with 5.25" backspace. With a little rolling of the fender lips, I have used tires 12" across the sidewall (MT 28/12.5-15 ET Street) and lightly rubbed the frame inside and fender outside on hard turns and dippy driveways. No damage, just rub marks. I'll be getting MT Street 275/50R15 next. they will have more clearance. Many 64-67 A body cars have been updated to the wider 8.5" rear ends.
We have the Big 3 Swap Meet in town the 25-28th of this month. I'll be looking for one of the 71-72 rears. 45th Annual Big 3 Auto Parts Exchange Thanks.
Larry, Will the offset for the 10" wheel of 5.625 fit without trimming the quarter lip and take care of any other tire rub issues ? I guess tire size would be a issue, at some point there would be a size limit ?
Rich, I see the term offset, and back spacing used interchangeably. They are not the same. They are measured from opposite ends of the wheel. Years ago, Phil Sedlon (70gsconvt http://www.v8buick.com/member.php?u=142) something like a 325/50-15 Drag radial on a 10" rim. He used 5.625" back spacing. It fit with some very minor rolling of the lip, if I remember correctly. I'll see if I can find the thread. We have an FAQ Forum on this board. There are questions that come up repeatedly. This is one of them. We should have a sticky thread in the FAQ forum on this.
OK, here is one. Looks like he used 5 1/2" B.S. so far. http://www.v8buick.com/showthread.php?t=14509 And another, this one mentions the 5.625" B.S. http://www.v8buick.com/showthread.php?t=34990 There are pictures somewhere of those tires on Phil's car, but I can't find them right now.
Thanks, Larry, I willl remember that about offset and back space. I agree a sticky thread would be great. It seems that a few times a year I start looking into a 10" wheel, Im sure I'll be asking about back space and drag radials when I get the body back on the frame.
