backspacing ?

I know this has been asked before im sure hundreds of time but, if im running a 91 Toyota pickup 4x4 no lift and stock or close to stock wheels what backspacing do i need, i have 31x10.50xr15 now but im thinking about going to a 32x11.50xr15 what do i need to choose?

 

i like the mickey Thompson classic II here's the info

• M/T Classic II Wheel
• 15x8, 6 on 5.5 Bolt Pattern
• BackSpace 3 5/16 in.
• Max Load= 2000lbs
• Finish = Polished
• Hubcentric= No
• Offset = -30 mm

Will it fit? please help

 

stock should be 4.5"

those wheels will stick out quite a bit...

 

so the backspacing should be 4.5 and what about offset? so the smaller number backspacing the more the wheel will stick out?

 

yep smaller backspace sticks out more

 

and offset?

 

not sure about what offset you would need...

with our trucks, backspace is what you need to clear calipers and keep the tires from rubbing, etc...

i once found a graphic that explained offset and backspace on google... too lazy to look for it again...

 

yeah i found where a site was saying like 3 3/8 bs my rims are wide deeper in the back than the front now, but back spacing is how deep the rim goes back behind the plate where it touches the axle