Backspacing

[awake1630]

The stock steel rims on a 97 K2500. What is the back spacing. They are 16x6.5 right? what is the back spacing.

[Husker 6.5]

The stock steel rims on a 97 K2500. What is the back spacing. They are 16x6.5 right? what is the back spacing.

That's the right size. I don't know back spacing off the top of my head, but it is easy to find. Drop your full size spare or pull a tire and rim off. Lay it face down. Put a straight edge across the back of the rim bead to bead. Measure down to the mounting pad where it touches the brake drum, or rotor center if a front. This is the back spacing. Remember that if you go to wider rims to divide the increase in width by two and add this to your stock back spacing to maintain proper suspention geometry and loading on your wheeel bearings. Example: Stock back spacing for a 16x6 rim is 3". You want to put monster mudders on on 16x10 rims. New rims are 4" wider than stock, divide by 2 = 2" plus stock BS of 3" = 5" new back spacing for your new 16x10 rims! Of course, you will have to verify clearances. Hope this helps.
Husker 6.5

[BlazeGM4]

The stock steel rims on a 97 K2500. What is the back spacing. They are 16x6.5 right? what is the back spacing.

I do believe that the bolt pattern is 16" x 5.5 and when shopping for wheels most manufactures use offset measurment in millimeters. Depending on what size tries you plan on running offsets are normally 0mm to 25mm offset. I run 20x8.5 with a +14mm offset (Boss 301) on my blazer in the summer, however i wish it was 0 because the front wheels stick out by 1/8" compared to the rears.

[awake1630]

Mint thanks for the great explanation.
Wish more people could be as helpful as you.

Thanks John

[Husker 6.5]

Mint thanks for the great explanation.
Wish more people could be as helpful as you.

Thanks John

Our rims are 16" diameter by 6.5" width stock for 2500's, and either 6 or 8 bolt pattern depending on standard or heavy duty. Our fellow 6.5 friend, BlazeGM4, is from Canada and is partially right, they use the metric system for measuring and the JIL system markings on rims for sizing/offsets. South of the Free Health Care border (wish we had it) we use predominantly the english (inch) system for measuring diam, width, boltpattern size, and backspacing for aftermarket and OEM rims, with some exceptions for some import vehicles in metric.

As I said earlier, the purpose of backspacing is to keep the load properly centered on the wheel bearings and maintain suspension geometry. Ever see those little Hondas with the 13" rims sticking waay out of the wheel wells so almost the whole tire is outside out the fenderwell that certain owners think are so cool? A mechanic friend of mine just loves them because he replaces front and rear bearings, struts, and ball joints every 15-20k mi. on them. Low and wide may look cool, but without proper backspacing it's hell on the suspension. My C2500HD rides on 16x8 8 lug American Racing rims. The back spacing on the 1.5" wider rims is 1" greater than stock to keep them in almost the same centering relation as the stock rims. Hope this helps.

[sixnickel]

This old fart thinks just like HUSKER6.5. For over 30 years I have felt that reverse rims(thats what we called them in the old days) do not belong on the front end. It throughs the front end geometery way off.In a way it makes the front end a lot weaker and easy to break some thing. The rims and tires belong around the ball joints not out flaping around outside the fender! A truck with stock back spacing will take a lot more abuse before something breaks,bends.or wears out!!