tire size back spacing Q's

[mhn3773]

i have tried to search but i cant think of what keywords to use i tried the ones in the title and it didnt give me what i needed i have a...tracker =)

but i was wondering how u measure for back spacing and what to measure to clear and stuff? like say i wanted 31s i know they fit round wise but i dont understand how to measure for width and back spacing and stuff like that really really confused lol

 

[Alec]

3.75" BS is a good backspacing to use with 15x8 rims.

 

[mhn3773]

i dont get where that number comes from though i know if i get it wrong they will rub on my suspention right? but if i put them to far out my car will look stupid..not that it already doesnt lol =)

confusing........

 

[Robb]

See if this helps: