Tire and Wheel Measuring

[scuba0331]

I have a 1974 Duster with a 66 B-Body 8 3/4 and I am attempting to measure for new tires and wheels. This is what I have done so far.

1. Used a plumb bob from the top of the inside rear quarter lip. I measured 4 inches to the drum mounting surface.
2. Measeured from the plumb bob to the spring and this is 11 inches.
3. Basically I have 11 total inches in the wheel well to play with.
4. So I came up with the following spreadsheet in which I calculated tire width and back space/front space %. Does it seem reasonable?
5. So I am thinking a 7.5" Rim with 5" of back spacing. I will be able to use a 255-60-15.

Does this seem reasonable? Thanks,

Rim7.5Back Space5Front Space2.5Back Space %66.67%Front Space %33.33%Tire Width10 Back Space Tire 6.67 Front Space Tire 3.33

 

[66cuda]

Very reasonable!! I did something similar.... BUT while tire mfgrs list thier tire specs as accurate there is room for variation and there usually is variation. some in their specs some in your efforts and some in the car itself.......if you are ordering these tires online....visit a local store and try to find a set of used tires in the size you seek BEFORE you order....put them on the rims then put them on the car...BOTH SIDES one at a time is OK...but fit the new shoes before you buy...especially if buying/ordering online. Many many stories of tires beig bought online that you are now stuck with because they are not exactly as specified due to rim width, run specs who cares!!! if they dont fit they may as well be SQUARE..... fit the shoes before you buy
good luck

 

[scuba0331]

Thanks Devil Dog! So I will "try on the shoes before I buy"!lol! I like the analogy!

I am buying the rims and tires from Summit Racing as the Tallmadge, OH store is only about 20 miles from my house. Worse case scenario I sill stuff the rim to check clearance. Stuff in the tire and than I will pray that everything still works after I have them mounted. Or I will have $600 worth of rear rims and tires that aren't worth a darn!

The spreadsheet is much more impressive than what I posted but it got all "garbled" up when I tried to copy and paste it.

I used a plumb bob, tape, straight edge to come up with my calculations. Also, I cut some wire hangars to simulate the the width and height of the tires.

But, like you said manufacturing specs may be different!

 

['64 Cuda]

All sounds good, but I suggest you take measurements on both sides of the car. You might find a big difference from one side to the other. I thought I had mine all figured out & then I measured the other side & the difference was huge. Went to the back of the car & bounced it up & down a few times & remeasured & it evened out. The suspension had shifted to one side when I put it on the jack stands.

 

[scuba0331]

All sounds good, but I suggest you take measurements on both sides of the car. You might find a big difference from one side to the other. I thought I had mine all figured out & then I measured the other side & the difference was huge. Went to the back of the car & bounced it up & down a few times & remeasured & it evened out. The suspension had shifted to one side when I put it on the jack stands.

Great idea thanks!

 

[66cuda]

I did say BOTH sides...right? What 64 said is what I was eluding to..... the difference between my left & right sides is about 1 inch..... everything lines up with a laser and it is still different..... TRY ON BOTH SHOES BEFORE YOU BUY!! of you will have some very attractive, very expensive boat anchors.

 

[pgkeating]

I had a set of wheels made for my '68 GTS:

The guy I used makes the wheels for both Stockton and Wheel Vintiques and he was cheaper.

I was able to speak to him prior to him making up my wheels, to double check my math/research. He's a wealth of knowledge and I like buying from a small biz guy.

So if you haven't bought your wheels yet, PM me and I'll send his info over. FWIW, several other members have used him too and were VERY happy.

I didn't want to post his anme here, for fear he'd lose the business he gets from the big wheel houses like Stockton.

Let me know.