Can anybody tell me if they have tried to fit an 8.5" rim width on a 68-69 GS? The low rear wheel well makes it tough to clear big tires. I tried the rims w/o tire installed and there is about a 3/4" clearance. Hate to find out the tires wont clear after buying them. Looking at slicks or drag radials. Dan
The rims I have are 5.5" backspace. I should have posted that. Thats why I was afraid to mount tires. Might rub the inside. What tire clearance do you have in the back of the wheelwell with "factory" backspacing? Dan
5.5 BS will be too much and will rub on the inside, 4.5 BS with the 8.5 wide wheel will rub on the outside. 15x8.5 with 5" BS should do it, but it will still be close on the outside. An 8" wheel with 4.5" BS will prolly be best.
Take a framer's square or other straight edge and put it on the brake drum vertically. Measure from it's edge to inside frame/inner fender (the closest point) and to the fender lip on the outside. Then take the section width of the tire you'd like to use (http://www.tirerack.com has a chart of specs. Products/Tires/Brands/Specs) and deduct the wheel width from the Section Width (10.2 SW - 8" = 2.2") and divide that number by 2 (2.2/2 = 1.1"). That will tell you how much 'bulge' on the tire from the lip of the wheel on each side. So, if you have a 255/60-15 with 10.2" SW and an 8" wheel it will be 1.1" closer to the inside frame than the amount of backspacing you choose. With 4.5" back spacing it will be 5.6" total width on the inside. I'd recommend a bare minimum of 3/4" clearance but I know others go with less. That would require at total distance (from your first measurement) from drum to nearest point of 5.6" + 0.75" = 6.35". Then with 4.5" BS on the 8" wheel you have 3.5" left on the outside, right? 3.5" + 1.1" bulge = 4.6" total + 0.75" for clearance = 5.35". So with all that totaled up: 5.35" + 6.35" = 11.7" from fender lip to inside frame needed. Of course all this changes if you choose a different tire size (245/60-15) because the section width will change, bulge will change, etc., etc. Hope it makes sense. :Smarty: I've had to go through this because I have a non-original 12-bolt in my GS and the usual measurements might not apply. Better safe than sorry.
