I recently picked up a 67' LARK skirts didn't come with mine. So I'm thinking about putting a nice set of tires & rims on it. I was told the largest I could put on the rear w/o modification is 275/40zr18. Is this correct information?
Thank you for responding, I was asking the same question to others and I got a few opposing answers. Someone with a 67' Chevelle told me yes but the fenders were rolled and he had 295's. So I definitely don't want to end up wasting money on the wrong size.
I've got 275/60-15's on my blue '66. Fender lip is rolled and wheelwell chrome is trimmed. I can barely fit my fingertips in there, but it 'fits'. Wheel backspace needs to be perfect for tires that big. If suspension is lowered, clearance will be tight on the inside part of the wheelwell near where the trunk body mount is. It might be doable.
If a 275/60-15 fits, a 275/40-18 might. It all will depend on correct back spacing. You should figure that out first. You'll need to specify wheel width for starters.
I didn't think it would fit, so thankfully a friend let me use his to try it out 18x9 275/40zr18 fit but the fender would definitely need to be rolled the offset was 8mm. So I think I can get away with 275/35zr18 for sure.
Offset and back spacing are not the same. Back spacing is measured from the back side of the rim to the mounting surface. Offset is measured from the center width of the wheel to the mounting surface, and there is positive and negative offset. 8mm is about 1/3" so that 9" wide wheel either has 4.2" or 4.8" of back spacing. You need at least 5" of back spacing on an 8" wide wheel so your test wasn't really valid. The P275/40R-18 tire and a P275/35R-18 differ only in height. The 40 series tire just a bit taller than the 35 series tire. They both have a section width of 275mm, about 10.8". You need the exact back spacing, and I would go with an 8" wide wheel. That is fine for a P275 tire. I would ask Walt what wheels and back spacing he is running on his 66.
I just went through this on mine. An 8" wheel is centered in the well with 5.5" of backspace. That's obviously a custom wheel. I'm running 235/50/17, could probably go to 245's. Make sure to check that body is centered on frame...many aren't. Mine wasn't and I had to plan for the side with the least space. I wouldn't necessarily rely on 66 comparisons...apparently they have 1" narrower rear ends up until late '66 anyway. Maybe Walt can confirm.
Agree, 5.5" backspace should work well for an 8 inch wide wheel, but you have to check your car to be certain! I've read '67 rears may be wider, but I can't confirm with the limited number of '67 rears I have..... I have only ONE! I have a '65 GS, bunch of 66's a '64 Olds F85 and a '67 Sportwagon rear. They are the same except the '64 Old is an inch or so narrower. Also have a '66 Chevelle 12 bolt in my blue '66 that is narrower than the Buick rears. Note that when measuring backspace on a wheel, a 7 inch wide wheel (7" between outside of tire beads) is actually 8" wide when measured from outside edge to outside edge..... and backspace is usually based on that 8", not the 7" tire bead width. My 275's are on 15x7 Buick rallys and a Chevelle 12 bolt rear. Wheels have 4-3/8" backspace and the narrower rear pulls them in 1/2" on each side. So figure, for a stock Buick rear, 5" bs for a 7 inch wheel, 5.5" bs for a 8 inch wheel and 6" bs for a 9 inch wheel....... This is a guideline only! Your combo could vary! There are tools avail to simulate wheel/tire fitment. Do a search (Google or Youtube) for "Percy's WheelRite Wheel and Tire Fitment Tool"
Note that when measuring backspace on a wheel, a 7 inch wide wheel (7" between outside of tire beads) is actually 8" wide when measured from outside edge to outside edge..... and backspace is usually based on that 8", not the 7" tire bead width.
