Size 13 x 6 is for a 3″ offset wheel
Size 13 x 7 is for a 2″ offset wheel
Size 13 x 8 is for a 1″ offset wheel
How to Measure the offset of your Wheel:
Wheel offsets were set back in the days before splined wheel centres and direct mount hubs, remember that when measuring the offset of your wheel.
Put a straight edge across the back edge (or inside) of your wheel rim.
Then measure from the straight edge to the back face of wheel centre NOT including the flange.
(Both Weld and Vahlco have a 1-3/8” bearing flange on their front hubs and a 1” splined flange on their Midget rear wheel centres (2” for Sprintcar rear wheels) – Do NOT include these flange’s in your measurements).
If using direct mount front hubs, you need to have your wheel mounted onto a hub in order to measure it correctly.