I was just wondering what i could do to check if the scuff is detrimental to the performance of the rim. There is a leak in the sidewal of the tire and i'm not sure if it's the seal on the rim or the tire itself

 

I'd be very wary about that. You could always take it to a rim shop and have them re-mount the tire. It should only be like 10 bucks.

 

You need to find out if the leak is a result of the scuff or if there is a hole in the tire. I the rim is not holding air, you would need to get the rim professionally repaired which will cost at least $50 (if you could do it locally, otherwise you have to pay to ship the rim also).