I'm going with a 225 or 235 60R15 tire. What backspacing do guys have on your front 15x7's? Picking up wheels tomorrow and just seeing what's typical for them. Going on a 68 Skylark. Thanks in advance.
Thanks. I'm getting the 4.5's on back but thought the fronts maybe different. I can pull one of mine in the morning and check, just trying to cheat and save a step, lol.
Thanks 72STAGE1. I'm using Torque Thrust D's not an original wheel if it matters. Their 15x7's are 3.76 bs. So just curious if there's a range people use.
4 3/8" is stock back spacing on the 15 X 7 chrome wheels. Aftermarket 15 X 7 wheels have 4", Aftermarket 15 X 8 has 4 1/2" back spacing. https://www.summitracing.com/parts/...laqwp9i01MN447tJgYzwPNxQv2Pmd97xjTeWTL-uO2FRg https://www.wheelvintiques.com/cata...1/s/15-x-8-buick-5-4-3-4-chrm-4-1-2-quot-b-s/ Realize that 15" wheels never came on 68 and 69 cars, they were 14 X 6 wheels, and they had 4 3/8" back spacing. That means that a 7" wide wheel would need an additional 1/2" of back spacing because of the addition 1" of wheel width (to keep the wheel centered in the wheel well). An 8" wheel would need 1" more back spacing. So for the 15 X 7" wheel going on a 68-69 Skylark/GS, you would want 4 7/8", and on an 8" wheel, 5 3/8"
Thanks for all that info on specs. I haven't had a chance to pull my current front wheel to see what it is and I'll see what my options are with the TT D's. I just don't want the 205's up front.
I have a similar question--trying to figure out the backspace difference between my original 15x6 non-rally wheels (on a '71 Rivi) and the 15x7 Buick rallys I'm putting on. But I'm not sure whether the wheel chart/appendix above applies only to rally rims, or to all wheels. I know the 15x7s have a 4 1/4 inch backspace, but I'm having a hard time getting an accurate measure on the original wheels (without taking the tires off the wheels). If the chart is right, the 15x6s should be 3 7/8 inches. Does anyone know if the chart applies to all wheels or just rally wheels? Thanks.
You should not have any problem at all measuring the wheels with tires installed. All you need is a thin piece of scrap wood, furring strip, or something similar. Cut it to length so that it lays on the rim edge, and measure down to the mounting surface. I would guess as long as the rim widths are the same, so would the back spacing, but you should confirm that.
Thanks Larry. If the chart works and the 15x6 rims have a 3 7/8 inch backspace, is the total difference to keep the 15x7 rims centered the same 3/8 + 1/2 = 7/8 inches?
A 1" wider rim would require 1/2" MORE back space to maintain the same centering in the wheel well, so 3 7/8" + 1/2" = 4 3/8"
