I think its min offset 3in, has to be the same offset left to right

It looked to me like the 77 super stock was a chain reaction victim on the restart. 2nd position on back started before the leader and had to check up. This is how the 7 and 5 got into trouble too.(5 passed early) I think they would have less trouble on restarts if they would throw the green midway down the backstretch like ISMA did. Great night of racing though as all classes looked very fast. Funniest part of the night was when 55ss touched someones rear that got out of shape in front of him and his hood popped up over his windshield.

As far as I know they are checking back space and there is no minium, but you are SUPPOSED to maintain a wheel track width within an inch of the OEM spec. The lower the backspace the wider the track width. The rules say you must run the same backspace on both sides of the axle. Some guys are following that some are not, as far as track width goes. if you run a 2" back space your car will be 3" wider in the track width ( I think) 😉
The 77's rearend did the big gernade, Matt was saying they losing it and hoping it would hold together. You could hear it quite loudly on the pace laps and even under green :'( it was only a matter of time! It really is too bad for them as they are top shelf performers