The bolt pattern, lug pattern, or bolt circle is the diameter of an imaginary circle formed by the centers of the wheel lugs. Bolt patterns can be 4, 5, 6, or 8 lug holes. A bolt circle of 4×100 would indicate a 4 lug pattern on a circle with a diameter of 100mm. The bolt pattern is comprised
of two numbers – the first indicates how many bolt holes are on the wheel, and the other describes how far apart they are. A bolt pattern of 5-115mm would mean the wheel has five bolt holes and they are 115mm apart (measured across the center of the wheel). Dual Bolt Pattern: More and more manufacturers are building their wheels with two bolt patterns. This expands the number of fitments the wheel applies to. For example: a wheel with a 4-100/114.3 bolt pattern has 8 lug holes and will fit both 4-100mm and 4-114.3mm fitments.
Measuring a 5-bolt pattern: A 5-bolt pattern is very difficult to measure without using a bolt pattern gauge. Basically, you would measure the diameter of a circle that crosses through the center of the lug holes. This method is not recommended to confirm wheel fitment. Please use the below as a reference only.
The offset of a wheel is the distance from the mounting surface of the wheel to the true centerline of the rim. A positive offset means the mounting surface of the wheel is positioned in front of the true centerline of the rim / tire assembly. This in effect brings the tire in to the fender well more. Conversely, a negative offset means the mounting surface of the wheel is behind the true centerline of the rim / tire assembly. This will cause the tire to stick out away from the vehicle.
H = High Positive or FWD (Front Wheel Drive) typically +45,40,35 offsets
M = Medium Offset or RWD (Rear Wheel Drive) Typically +20 offset
L = Low Offset or RWD (Rear Wheel Drive) Typically 0 offset
Plus sizing your wheel & tire combination was designed to enhance vehicle performance and looks by allowing fitment of larger diameter rims and lower profile tires. The theory is that while making these changes, you keep the overall tire diameter within 3% of the original equipment tires. This is important because larger variances can cause problems with transmission shift points which can decrease fuel mileage. It can also confuse braking system computers which can even lead to brake failure.
Here’s the rule of thumb for “plus sizing”:
- Plus 1:
Increase section width by 10mm
Decrease aspect ratio by 10 points
Increase rim diameter by 1 inch
Increase section width by 20mm
Decrease aspect ratio by 20 points
Increase rim diameter by 2 inches.
- This is not exact,