ok guys, heaps of people have been comming up to me, either asking me "what offset do you think my rims are?/what offset should i go with to get new rims?"
umm, hello0o0o! just because i used to work in a tyre shop, doesn't mean i can tell the offset just by lookin at it, i cant remember the whole book and all the measurements ive taken on a particular car to work out the perfect rim size/offset for yours..
and aswell, some rims dont have their offsets printed on them, especially custom rims/2-piece or 3-piece rims (as in my case)
well just to be nice, here is a little tutorial on how to measure the offset on your rims if they havnt got anything stamped on them, ii hope its not to difficult to follow..
1st, get the rim, and measure the width across from one side to the other side. remember, just because the rim is 7.5", it doesnt mean its 7.5" from one edge to the other edge, its only 7.5" from the 2 inner lips. In my case, this is 318mm
or if there is a tyre mounted on the rim, lay the rim down on a flat surface & put a straight edge across the top of the rims and measure it from the ground-up through the spokes of the rims to the straight edge on top, but the 1st method is more accurate. if you could, try and deduct the overhang of the tyre on the edge of the rim on both sides.
now take that measurement and divide it by 2, that is the measurement of the centre line, which we will use further on in the tutorial. In my case, this is 318 divided by 2 = 159
now lay the rim down "FACE FLAT" on a level surface and measure the backspace of the rim (the face of the hub mounting surface to the rear edge of the rim). In my case, this is 150mm
Ohkay, now get the backspace measurment (150), and subtract the centreline measurement (159) and the answer is your offset (-9)
hope this helps you people out, and it wasnt a total waste of your time reading it
Can someone help me out and tell me what + offset they get with these measurments?
Thanks A lot!
Last edited by Accordlayingkit; 18-06-14 at 12:50 PM.
Yes good point on the rim size too... outer edge to outer edge is not the rims nominated width. The nominated width is measured between the lips that the tyre bead seats on!
in most case an inch less than outer measurement. I made this cross section diagram some years ago. feel free to use.