Wheel well sizing request

[march11934]

Hello everyone. This is my first post in this forum. I have really enjoyed reading and learning from this posts in this forum, however I can't seem to find any info on wheel well specs. I have a 70 Cuda that I intend on building up to pro touring. I am currently working on the back half of the car. I have been collecting tire info from various posts on this forum and 18 inch rims seem to be the most popular. Looks like a 305 to a 335 width is the tire of choice. I'll probably be going with a 45 for a little sidewall height.
That said I need your feedback on what wheel well specs your running to fit a 12'ish in wide tire?

An e-body rear frame rail runs in a splayed layout. I don't know why... so it starts narrow at the front and works out wide as they progress to the rear bumper. This causes a bit of a problem when measuring out for "potential" growth if widening the wheel wells, which I intend to do. Without touching the frame rails I can get just about 14 inches wide stretching to the rear portion of the frame rail. There would be more room to go it they were more parallel. This should fit a 335 but I don't actually have a set to mock up. Thought about buying a burned up set from a junk yard...



I have considered removing the rails and shifting them more parallel but not sure it's worth getting into if the wells don't need to be wider than 14 inches in the first place.

Any specs on wheel well sizes for a 335 tire would be great feedback.
Regards.
march11934

[USAZR1]

Who builds a 335/45/18 tire? I've seen a 335/30 but nothing else. Michelin and Nitto both offer a 345/30/19. Michelin also offers a 345/30/20.
Welcome to the site. Where do you live?

[march11934]

Good point on the size. I haven't committed to a final size yet so I was trying to not be specific in any one tire size. I know I would like to reach a 12 inch width. 18 in rims seems to be very popular and from what I have seen fits the e-body well. Anything bigger just doesn't seem to go right for my taste. thats just my opinion. First gen Camaro's pull it off well but Cuda's not so much. Don't know why.
Currently in NC.
Thanks

[march11934]

So anyone out there with a 12 inch tire and a tape measure? It's the first time I am minitubing a car and was hoping for some advice on any gotchas I might not consider.

[dontlifttoshift]

According to tire rack, a 335/30-18 measure 13.5" when mounted on a 12" wheel. If you leave 1" of clearance to the inside and 3/4" to the outside that means you need a wheel well depth of 15.25" minimum. You have to keep in mind that you need that depth not just at axle centerline, but for the whole diameter of the tire. That tire is 26" in diameter so you need 15.25" of depth 13" forward of axle center line and 13" rearward of axle center line. You also need that depth 13" above axle centerline _plus_ suspension travel. All measurments taken with the car at ride height.

A 335 will not fit in your 14" width. A 315/30-18 or a 305/30-19 will fit but your backspacing will have to be right on and I probably wouldn't run that clearance with leaf springs unless you just plan on cruising.

If you are doing the tubs anyways, it really isn't that much more work to notch the rails. There is even a kit from US Car Tool http://store.uscartool.com/70-74-MOP...Kit_p_142.html They claim 355/30-19 with their tub kit, I feel that is optimistic for a car that would get driven in anger but a 335 would work with perfect backspacing and proper suspension design.

[march11934]

Hey Donny. Thanks for your time on the answer. I'll be making some additional measurements to see how this all aligns with your specs.
I have one wheel well out and going to start trimming some metal to what I can get away with without cutting into the rails. Will see.
Best.