I'm thinking seriously about putting 15" Ansen Sprints on my 1955 TBird. I will not be using fender skirts.  Does anyone know what width and backspacing I will need?  My car currently has 215 70R 15 tires and they only rub when backing tightly. 

I’m running 15x7 3 1/2” backspace Salt Flats on the front, and 15x7 4” backspace in the rear. 225/60 15’s and 235/60 15’s respectively. Doing it over, I’d probably stay with 6” rims. The upper ball joint to sidewall is very tight in front, and the rears are tight everywhere. I’m not running leafs in back, but IIRC, that’s also a limiting factor on the rear of the leaf spring.

It’s difficult to tell from the picture, but I can’t get a finger between the sidewall and the ball joint. It was that close before I modified the b/j mount too.



miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Tire width doesn't change a whole lot as long as the tire is on a rim within the recommended width range so a narrower wheel may not help much.  There are spacers that can be used to help fine tune wheel positioning so long as there is room on the outside..


Lawrenceville, GA

I guess I should have added I’d go a little narrower on the tire, too. There’s no room with my combination to adjust with spacers. The body was1/2” or so off center from the frame, and I had to move it over for the combo I have. It’s about as close as I’ve cut it and gotten away with it. Next step was rolling the lip on the wheel wells. I’ve done that before.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

My car's suspension is completely stock except for gas shocks.  I'm looking at 15" x 7" wheels with 4 inch backspacing and 225 70 R15 Radial TAs all around.   Do you think this will work?

Here is basic tutorial - https://static.summitracing.com/global/images/instructions/crw-35-580547500.pdf

It can get very complicated and goes well beyond this without having to modify sheet metal. As mentioned, the body has to be centered on the frame, the suspension cannot move during turns and  must be modified to not let it squat on uneven road. You have to measure once you know desired trim height. Tire sizing charts are available from tire manufacturers.There are many special tools available for this.

You cannot really go off what someone else has done and got away with. Once you order special offset wheels, they are yours.

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I’ll second K’s statement, you really have to measure your car. Too many production variances and repairs over the years. My gut feel is you’re going to be really marginal with that combination. I can guarantee the 4 “ backspace in front wouldn’t clear my car.

There’s a regional tire store in my area, and if I drive by the closest 2, the 3rd store is run by a hot rod guy. He measured the car for the wheels, and guaranteed they’d fit. He’d reorder at no cost to me if he got it wrong. That helps. We did have to do some grinding on the front wheel to clear the caliper on the disc brakes. Not the first time I’ve seen that. He picked up the warranty on the wheel for that.

Some disc brake conversions move the wheel mounting surface out a bit, just something to keep in mind. I’ve rolled a number of fender lips on tri five scrubs due to this.

Here’s a typical fitment tool. For a one time deal you can make up your own out of plywood and coat hangers. You still have to eyeball suspension travel, turning, etc.

https://www.google.com/search?q=tire+clearance+measuring+tool&client=safari&hl=en-us&prmd=simvn&source=univ&tbm=shop&sa=X&ved=0ahUKEwjl57WHsMreAhWCEnwKHUnLBwQQ1TUIQA&biw=1024&bih=643







Number 3 and 5 as you scroll down.



miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I decided to go with the stock wheels 215 70R 15 Radial TAs and dog dish hub caps.   Love it!!

I think it looks great. I used the dog dish caps on a couple wheel combinations, I still like them.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Hope I didn't kill your dream.

It can be done but a lot of work is required, especially on a chassis as tight as this one..

She looks nice!

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