What fits under my 71 Centurion?

I need to find some sticky tires for my car when I go to the track. I'm tired of roasting my wide whites. And I just bought a fresh set too.

Going by the fact that I know almost nothing about tire sizes and backspacing on rims, where does one start? I would imagine that I could fit whatever size you Skylark GS guys can stuff under there. I wouldn't imagine that my wheel houses are smaller than yours

Also, I need two 5 on 5 rims to mount the tires....but is backspacing going to play a part in judging what tire I can put on? How about a stock ralley rim? 15x7 - can I put a 9 or 10 inch tire on it?

 

What fits under your centurion?

Uh, just about any import, I imagine.:grin:

-- Steve

 

:laugh: :laugh: :laugh: :laugh:


Priceless! ROFLMAO

 

I am trying to remember but I believe the wheels you have are 15x7. They are 7 inches between the beads and 8 inches total rim to rim. Wthout changing wheels you can get a 10 inch slick under there no problem with clearence. It will be a little baloonish and might not have an even tread pattern. My Centurion has about an inch of positive clearence between the fender and I would imagine yours does too. The best thing to do is measure your wheels negative backspacing. To do this you need to lay the wheel backside up. Place a straightedge on the back of the wheel (not tire) and measure from the mounting face to straight edge. This will give you your backspacing.

If you have a 7" wheel with a 4" backspace you have a 0" offset wheel. With the wheel on the car you may have say "3 inches" of clearence. Take into cosideration sidewall flex and we'll say 2 inches. That will give you a backspace of 6 inches and a total wheel width of 10". That was just an example. You will have to measure your car and wheel for the exact width and backspacing. Hope this helps a little.

 

Stockton Wheel has 15x8 OEM steel wheels for $90 a piece.

What width tire can I put on there? 9":Brow:

 

I can only guess that the sotck size on it now is 15x7?? They're just the stock steel wheels.

Also, other measurements:

Backspacing: ~3 7/8"

Fenderwell clearance: ~2 1/4"

Frame clearance: ~1 7/8"

 

If you go with that 15x8 and by the measurements on your clearence you can put a 10" slick under there with about 1/2"of room. It may rub if you drive on it from sidewall flex but for the track you will have no problems. Remember with a drag slick it expands in the center and contracts the sidewalls in at exceleration. WARNING! use my sugestions at your own risk. May induce tubing or axle narrowing!

 

Adam, if you have the stock rims, then they are going to be 15x6. I'm pretty sure you have to look at late 70's-early 80's Estate Wagons for stock 15x7 5" pattern rims.

 

73 Riv GS Rims

Adam, didn't you get your rims from a 73 Riv GS? Those would be the 15x7, and hard to find acccording to TopCat. He's running 275-60-15's on his Wildcats with a pretty big spacer to get the tires out from the frame. I think the spacer is 1.25"; there is a thread here somewhere... http://www.v8buick.com/showthread.php?s=&threadid=23932&perpage=25&highlight=spacer&pagenumber=2

He doesn't say what the spacer width is there, guess I gotta go ask him at a chassis tech session!

 

They are acutally off a 75 Olds Delta....

How does one measure them without slashing the tires off?

 

I was just thinking....


I won't be using the rims currently on the car. So I have choices as to what I need to get.

 

I have 235 70 15's all around on my 73 and there's lots of clearance. You should be able to find measurements for most tires on the manufactures web sites. That will tell you the tire height, and width. Try to find a tire of the same height as your wide whites to keep the speedo readings in line. Stuff as much width in as you can. If you remove the tire and put a straight edge across the mounting surface you'll be able to see where the clearance is tight. Measure the distance to the inside (probably the frame rail) and the outside (the top lip of the wheel opening).

Add them together and subtract what you want for clearance. For drag racing and straight line you can keep it tight, if you want to run on the street you'll need more clearance for axle shift around corners. Then find the tire closest to your ideal width.

Backspacing for your rims is measures from the mounting face of the rim to it's back edge. You want the backspacing to center the tire between the two clearance problems (inside and out). Again find a rim with the closest to your ideal number.

If your uncertain you can make cardboard templates, one disc that mounts like a rim and a tube that represents the rim. Mount your psuedo rim and shift the tube around till the clearance is what you want. Then you can measure the backspace. Once you've created the templates you can use them over and over on any car you want. This is particularly helpful with front rims as you can check the clearance lock to lock.