The most primitive part on any given vehicle is the wheel. It's the one invention that changed the face of transportation as we know it and got things rolling to where we are today. So why do these simple round masses confuse so many people? While backspacing, beadlocks, steel versus aluminum, hub centric, and lug centric are all part of the puzzle, the first and most basic item that's crucial to understand is wheel bolt pattern.
"Wheel bolt pattern" refers the number of lugs and bolt circle for a given wheel. This is determined by the distance of a circle drawn through the center of your lug nuts. For example, if your rim has an 8-on-6 1/2 bolt pattern, then 8 is the number of lug holes and 61/2 the diameter of the circle in inches.
For a closer look into the world of wheel bolt patterns, we've compiled a few basic tips for measuring the various odd and even lug rims as well as created a pattern guide for some of the most popular 4-bys on the road. Enjoy.
The Pattern
The most common wheel patterns for 4x4 vehicles are five-, six-, and eight-lug. Traditionally domestic vehicles have simple fractional distances like 5-on-4 1/2, 5-on-5 1/2, and 8-on 6 1/2. Many modern and foreign wheels have metric distances (millimeters) like 5-on-135 and 8-on-170.
| CONVERSION CHEAT SHEET |
| (1 inch equals 25.4 mm) |
| INCHES |
MILLIMETERS |
| 41/4 |
108.0 |
| 41/2 |
114.0 |
| 43/4 |
120.7 |
| 5 |
127.0 |
| 51/2 |
139.7 |
Even Lugs
To determine the distance between even bolt hole patterns like six- and eight-lug wheels, the formula is simple. Using a tape or ruler, measure the distance between the center of one lug hole to the center of the hole directly across from it-think 12 o'clock to 6 o'clock.
Odd Lugs
Figuring out a five-lug pattern can be a little tricky. The most common method is to measure from the outside edge of a lug hole to the center of the hole directly across from it. Another way is to measure from the center of a lug hole to the center of the hole directly across from it and then multiply by 1.05.
THE WHEEL CHART
| VEHICLE |
YEAR |
BOLT CIRCLE |
| CHEVY/GMC |
| 1/2-ton Pickup (gas) |
'57-'09 |
6-on-5 1/2 |
| 3/4-ton Pickup |
'65-'09 |
8-on-6 1/2 |
| 1-ton Pickup |
'77-'09 |
8-on-6 1/2 |
| Blazer/Jimmy/Tahoe/Yukon (Fullsize) |
'69-'09 |
8-on-6 1/2 |
| Envoy/Trailblazer |
'02-'09 |
6-on-5 |
| S-10 Blazer and Pickup; S-15 Jimmy, Pickup, Sonoma |
'83-'03 |
5-on-4 3/4 |
| Suburban 1/2-Ton |
'57-'09 |
6-on-5 1/2 |
| Suburban and Avalanche 3/4-Ton |
'67-'09 |
8-on-6 1/2 |