like the title said how can u tell what the offset is?????

 

If you look on the back of the wheel ( like on one of the spokes or something), it'll say the width and offset.

 

And some wheel comanies coughcoughraysengineeringcoughcough like to keep some of their offsetts secret.

 

You can measure the back spacing and calculate the offset. Example a 8" wheel with 4" of back spacing would be 0 offset, an 8" wheel with 6" of back spacing would be +52 offset ..... note I'm using round numbers for example... you can get close or really close depending on how you measure.