WHEEL FITMENT EXPLAINED Bolt Pattern The bolt 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 4x100 would indicate a 4 lug pattern on a circle with a diameter of 100mm. The diagram indicates the proper measuring methods for both 4 & 5 lug patterns. 6 lug wheels are measured like the 4 lug wheels. Conversion Table Inches - Millimeters 4 x 3.93-4 x 100 4 x 4.25-4 x 107.95 4 x 4.33-4 x 110 4 x 4.50-4 x 114.3 4 x 5.12-4 x 130 4 x 5.51-4 x 140 5 x 4.00-5 x 100 5 x 4.25-5 x 107.95 5 x 4.50-5 x 114.3 5 x 4.53-5 x 115 5 x 4.72-5 x 120 5 x 4.75-5 x 120.65 5 x 5.12-5 x 130 FTO Stud Pattern 5 x 114.3mm Centerbore The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. This hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration. With a hubcentric wheel, the lug hardware will not be supporting the weight of the vehicle, all they really do is press the wheel against the hub of the car. Some wheels use high quality, forged centering rings that lock into place in the back of the wheel. This is an acceptable alternative.
If you have non-hubcentric (lugcentric) wheels, they should be torqued correctly while the vehicle is still off of the ground so they center properly. The weight of the vehicle can push the wheel off-center slightly while you're tightening them down if left on the ground. FTO Centerbore 67.1mm Offset The offset of a wheel is the distance from its hub mounting surface to the centerline of the wheel. The offset can be one of three types. Zero Offset The hub mounting surface is even with the centerline of the wheel. Positive The hub mounting surface is toward the front or wheel side of the wheel. Positive offset wheels are generally found on front wheel drive cars and newer rear drive cars. Negative The hub mounting surface is toward the back or brake side of the wheels centerline. "Deep dish" wheels are typically a negative offset. If the offset of the wheel is not correct for the car, the handling can be adversely affected. When the width of the wheel changes, the offset also changes numerically. If the offset were to stay the same while you added width, the additional width would be split evenly between the inside and outside. For most cars, this won't work correctly and only a select number of fitments will work for your vehicle.
FTO Wheel offsets These are not 100% accurate, but pretty good guideline. Width 6.5 Offset +20mm to +50mm Width 7.0 Offset +25mm to +45mm Width 7.5 Offset +30mm to +39mm Width 8.0 Offset +35mm Standard FTO offset 38mm Proper Lug Nuts or Lug Bolts While many aftermarket alloy wheels are designed to use your carã â â s original lug nuts or bolts, others require new hardware. It may be something as critical as differences in the wheelã â â s lug seat design as shown below, or something as simple as shorter lug heads to allow the wheelã â â s center caps to fit. If your new wheels require new hardware, ask your supplier for the appropriate lug nuts or lug bolts and it's worth taking note of the the size, pitch, seat design, length and the appropriate lug wrench socket size, i case you need to replace them at a later date. NOTE: Keep a set of your vehicles original lug nuts or bolts in the trunk just in case you ever need to use your spare tire.
Wheel Lug Nuts Torque IMPORTANT! Proper installation requires that the wheel lug torque be set to the recommended specification for your vehicle. These torque specifications can be found in your vehicles shop manual or obtained from your vehicle dealer. Finish tightening the lugs down with an accurate torque wrench. Use a crisscross sequence (shown below) until they have reached their proper torque value. Be careful because if you over torque a wheel, you can strip a lug nut, stretch or break a wheel stud, and cause the wheel, brake rotor and/or brake drum to distort. NOTE: When installing new wheels you should re-torque them after traveling the first 50 to 100 miles. This is necessary because as the wheels are breaking in they may compress slightly allowing their lugs to lose some of their torque. Simply repeat the same torque procedure listed above. Rim & Tyre Sizes 16x6.5" - 205x50R16 **Standard 16" GPX Wheel 17x7" - 205x40R17, 215x40R17(offers more rim protection) 17x7.5" - 215x40R17 17x8" - 235x40R17 *** 225x45R17 ARE THE WRONG SIZE *** 18x8" - 225x35R18 Speed(mph) difference between tyre sizes. 205x50R16 = 70 mph **Standard 16" GPX Wheel 205x40R17 = 68.22 mph 215x40R17 = 69.13 mph 235x40R17 = 70.96 mph 225x35R18 = 70.38 mph If you use the tyres as suggested above with your rims then you should not have any trouble with the tyres rubbing in the arches. Tyre Pressures
As a general rule for every 1" increase in rim size I would add 1-2 PSI to the standard tyre pressures... 16's - 32F 29R *** Standard GPX Alloy *** 17's - 32F 29R 18's - 32F 29R Tyre pressures have been a long debated subject, there is still no deffinative answer, so if you are unsure always use standard factory pressures, then check the wear pattern regularly, and adjust where nessasary. The Big Picture This will show you all the dimensions at work.