I have a 15x10 rim with a 4.50 back space with a 295 50 15 tire the right side rubs when you hit a bump . I was going to mount a 275 60 15 tire on the rim to see if it will rub What is the backspace that i will need to fit a15x10 rim with a 60 sieres tire:confused:

You need a 5.5BS, not a 4.5BS - the tire is not sitting square in the wheelwell.

295/50/15 will fit with a 10 inch rim with 5.5 bs but i had to add a 1/8 inch spacer on my passenger side as it rubbed the shock, here are pics of my wheels
http://i15.photobucket.com/albums/a351/Tonystoys123/mean%20green/Picture277.jpg
http://i15.photobucket.com/albums/a351/Tonystoys123/mean%20green/Picture022.jpg
http://i15.photobucket.com/albums/a351/Tonystoys123/mean%20green/Picture274.jpg