Back Space on Rim Spec's

[Truword1]

Hey list, I've been reading almost every thread I can on rims and wheel size but my question that I don't understand is what do you mean by back space. For example (The rears are 17x9.5 with 4.75" of backspace with a 275/50. Up front is 17x8 with 4" of backspace and a 255/50). Can you please explain?

JD

[novajess1972]

Originally Posted by Truword1

Hey list, I've been reading almost every thread I can on rims and wheel size but my question that I don't understand is what do you mean by back space. For example (The rears are 17x9.5 with 4.75" of backspace with a 275/50. Up front is 17x8 with 4" of backspace and a 255/50). Can you please explain?

JD

If you were to lay a wheel on it's face (the nice part that everyone sees) and lay a ruler or something long and straight across the top of the wheel from outer edge to outer edge, then measure from the ruler down to the hub's (center of wheel) flat surface, that will be your backspace.

The more backspace, the more inward (toward motor) the entire rim goes. The less backspace, the more outward the rim sits. These numbers become important when choosing wheels/tires in order for them not to either interfere with inner fender well, disc/drum brakes, and other suspension parts.

I hope this helps and if anyone has a better way of explaining, feel free to add/clarify.

Jesse

[novajess1972]

Also, here is a link that can help clarify.

http://www.newstalgiawheel.com/glossary.asp


Jesse

[Truword1]

The reason I ask is beacuse I plan on purchasing some 20'' rims that are 8.5 and 5" backspace. What do you guys think? This is the only size availible in this rim and I just love them. But before I purchase I want to get you Pro's opinion. They'll be going on a 1970 C10 with a 4/6 drop. Please help.

JD

[Jayss109]

Measure, measure and measure again before buying. Find out the REAL size of the tires you want (Not advertised, find out the width at the bulge of the tire, which will change depending on the width of the wheel)

I am actually about to double check my measurements for the wheels I am going to order, just to make sure!!

J

[novajess1972]

Originally Posted by Truword1

The reason I ask is beacuse I plan on purchasing some 20'' rims that are 8.5 and 5" backspace. What do you guys think? This is the only size availible in this rim and I just love them. But before I purchase I want to get you Pro's opinion. They'll be going on a 1970 C10 with a 4/6 drop. Please help.

JD

Just so happens you are asking the right guy. I have 20x8.5 with 5 inch BS on front and 20x10 with 5.5 inch BS on rear on my 72 C10. I'm certain they will fit just fine. And I have a 4.5/5 inch drop.


Jesse

[Truword1]

Hey NovaJess1972, what size tire do you have and what size tire do you thing I should use with the 20" X8.5, 5'' backspacing? I'm trying to go for the level look.

Thanks
JD

[novajess1972]

Originally Posted by Truword1

Hey NovaJess1972, what size tire do you have and what size tire do you thing I should use with the 20" X8.5, 5'' backspacing? I'm trying to go for the level look.

Thanks
JD

I am running 255/45-20 on front and 295/45-20 on the rear. For your fronts, of course, I would recommend the same size that I am running, since the diameters and widths are identical. As for the back, not sure if you wanna make it look a bit fatter/meaner than the front or not???

If it were me, and I was running the same wheel on all corners, I would run the 255/40-20 or 255/45-20 in front and a 275/45-20 in rear. Eventhough these tires are all different sizes, they are all recommended to fit a rim with a width of 8.5-10 inches. Also it will appear that you have a bit wider wheel in the rear than the front.

Jesse