15 * 10 backspacing

[Velon]

this is probably the wrong section to post this in, but just wondering if anyone knows the correct backspacing or offset for a 15 * 10 for the rear of a grand national to run 275-60-15? looking to run 15 *7, 15 * 10. Thanks for the help.

 

[mytquick87]

G Body Parts. com uses 4.5" bs for a 10" rim and has some nice photos on his website of these.