trying to understand backspacing

[E-rock]

so i read the sticky but it still doesnt make 100% complete sense. im tryin to order new rims for my explorer so the tires dont rub anymore. right now ive got the stock 15'' alloys on my 01 4dr. the backspacing is 4'' i believe and the bolt pattern is 5 x 4.5 (i think its the same for every explorer made). but i want the rims to stick out wider. i think the stock rims are 15 x 7? im running 31 x 11.50's but im gonna switch to 32 x 13.50's after i lift the body in a few months. so how far should the backspace be? the diagrams dont make it clear which is the front of the rim and which is the back. i suppose if i get wider tires, the backspace will be less? correct me if im wrong but i think i should get 15 x 10 inch wheels with 4.75 backspace?

 

[FROADER]

Stock backspacing is 4.5" so ~3.75" would be best for the tires you want to run. The smaller the backspacing number, the farther out they will be. This will also put more wear on your wheel bearings, so make sure to check them regularly after you get the new wheels and tires.

 

[Dan Whitaker]

You want 3.5 or 3.75" of back space. 4.75" will move the wheel in too much and you the tires will rub on the upper control arm.

Curse you Colin you were just a splic second ahead of me yet you are 2 hours behind me

 

[E-rock]

ok so 3.75 is the distance between the edge of the rim where the tire is to back of the mounting point on the inside of the rim touching the rotor? and the less the backspace the more offset it is in the other direction?

 

[FROADER]

Right.

 

[spabula]

is 4.5" BS standard for all 95-01 Ex's?? 15's or 16"s??