Wheel backspacing

[r1_addict]

I am looking to put some American Racing Tork Thrust D's on my 73. For the rear I want to put 15x10 with a -43 back space and up front 15x8.5 with a -24.

I know factory is 15x8 -50 on a 5 bolt 4.75" Will I have any issues with where I want to go?

 

[cruisin-davey-g]

I am looking to put some American Racing Tork Thrust D's on my 73. For the rear I want to put 15x10 with a -43 back space and up front 15x8.5 with a -24.

I know factory is 15x8 -50 on a 5 bolt 4.75" Will I have any issues with where I want to go?

Hi: I may be missing something, here. I never heard of this type of backspacing. In my experience, I've always kept it simple when it comes to back spacing. Just took a measurement using a tape or ruller. Are these neg. terms for measuring back spacing used in actual machining of rims? As I'm no machinest.

Anyway, regardless of the type of backspacing, I really don't know if you can go to 15 X 10 rim, anyway, on the rear without going to the off-set trailing arms if you're trying to keep the rims & tires from sticking out from the body. If you're going the other way with rims & tires out from the body, then I would think that fender flares would be needed. Just my opinion.


Peace: Dave (To back-space or not to back-space, that is the question)

 

[69MyWay]

I guess you are using metric back spacing numbers.

I am running a 18x12 on the rear with a 5" off set, and 18x9.5 on the front with a 4.5" offset.

I also have flares and offset trailing arms.

With stock trailing arms, I would not push it past 4.75" on the rear. Otherwise you are going to be into your trailing arm and E-brake cable.

Remember, Vette Brakes and Products makes spacers to allow you to put C4 and C5 wheels on a C3. Those wheels are 9.5" wide, which means they are actually 10.5" wide lip to lip. There is a difference between adverstised and actual width.

I see no reason why you can't get a 9.5 or 10" rim in the rear with some careful planning.

 

[cruisin-davey-g]

I guess you are using metric back spacing numbers.

I am running a 18x12 on the rear with a 5" off set, and 18x9.5 on the front with a 4.5" offset.

I also have flares and offset trailing arms.

With stock trailing arms, I would not push it past 4.75" on the rear. Otherwise you are going to be into your trailing arm and E-brake cable.

Remember, Vette Brakes and Products makes spacers to allow you to put C4 and C5 wheels on a C3. Those wheels are 9.5" wide, which means they are actually 10.5" wide lip to lip. There is a difference between adverstised and actual width.

I see no reason why you can't get a 9.5 or 10" rim in the rear with some careful planning.

Hey Chris: Eighteens? Holy Moly! And I thought I was gonna have trouble with the seventeens I've got. What size tire are you running up front? Whats the tire height & shoulder width of your fronts?

Dave

 

[69MyWay]

My fronts are 275 35 18.

You can go to the www.michilen homepage and download a chart that gives the physical height and width of the different tires. I am running the pilot sports. Excellent tires.

It does not matter if you are 15,17,18---20" rims. The rim diameter does not affect anything. The width and offset is all you need to be concerned with.

If my car was stock fendered, I would go with offset arms in the back and run 5" back spacing on all four corners with 9.5" or 10" rims and 275 35 on the front and 285 or 295 on the rear.

I think the front tire is right under 25" tall. My rear tires are right at 26" tall. 335 30 18.

I am not sure what you mean about the shoulder measurment.

 

[LIRacer]

I agree with Chris. I went the with offset trailing arms and used 15 x 10 inch Torgue Thrust D Chrome. I liked the period correct look of 15s rather than a wider diameter. The view from the rear is awsome. I cant load the pictures on this forum as they takeup too much memory. Send me your email address and I'd be happy to send a few.


Bruce

 

[cruisin-davey-g]

I think the front tire is right under 25" tall. My rear tires are right at 26" tall. 335 30 18.

I am not sure what you mean about the shoulder measurment. [/B][/QUOTE]


Hi Chris: Shoulder Widht: There is tread width & shoulder width. Some, but not all, tire companies use this term in their measurements. Shoulder width is the total width of the tire (sidewall to sidewall measured across). Tread width is just the width of the part that hits the ground. I have always found that the lower profile the tire, the more tread width (thus better handling & response to the road). Also, the lower profile, the closer the tread width is in conjuction to the shoulder width because of the lack of sidewall buldge. 70 series tires will have a bigger sidewall buldge that, say, a 50 or 45 series tire.

I found that on my '72, I can't go much over 10" shoulder width otherwise I found that I give up some turning radius (tires hit) & also, some rubbing will occure within the fender well. The stock tire which came on a standard '72 was approx. 27 1/2" tall (F70 X 15). Shoulder width for that tire was below the 10". I went to a larger size tire & at that point, I couldn't put a bigger tire than a H60 X 15 (P23560R X 15) & not have it rub. Of course, it was a slightly taller tire, but the shoulder width was still under the 10".

This is my basis for going to a 17" rim (17 X 8 - 5" BS). Also, in order to fill up the wheel wells with tire & rim, I found that the only tire in this size that will do that & not be too wide (in the front) is a passenger tire (size P235 55R X 17) the height of this tire is approx. 27" tall: tread width: 8 3/4": shoulder width: 10". Should work pretty good on the front & be as close to the stock tire as possible.


Peace: Dave (Thanks for the web site to that tire site)

 

[elseyj]

Bruce,
What backspacing and tire size are you running on your 15-10s?
Jim

 

[mmitzan]

wheel backspacing

Here is the best definition I have seen
http://www.classicindustries.com/tips/tip009.htm