Backspacing vs offset

Excuse me guys for being a retard but i,ve never really worked with wheels or tires. I have a couple of questions. What is the difference between backspacing and offset? (I've seen offset on truckperfomance.com) Also, how does backspacing work? Is it that the smaller backspacing you have, the further out the wheels stick, or the other way around? Also, with a 2" lift, i would like to get a 31x10.5x15 tire on a 15x8 rim. What backspacing will i need to avoid rubbing and still stay fairly stock looking( in terms of the wheels sticking out)? Thank you for the help, i appreciate it!

 

[Creager]

4.5" stock backspacing... which is what i used after a 3" body lift. They stick out a little bit (15x8 wheel compared to 15x7 stock"

i was always under the impression offset/backspacing is the same thing. But according to this picture, they are indeed not

 

[briwayjones]

In that picture which side is the inside of the rim?

 

[Jason94sport]

I'd say the left side. I also thought BS & offset were the same thing just one was in MM the other in inches. It's hard to find 15X8 rims that have a 4.5" back space. Most people go with 3.75" & most rims come that way. They will stick out past the fenders a little more.

The lower the number offset or the lower in inches the farther the rims will stick out.

 

[etc]

Backspacing : Distance from the backside of the rim to the mounting surface.

Offset: Distance from the centerline of the rim to the mounting surface. Not sure which way is positive/negative.

The left side if the inside of the rim in the picture.

 

[Creager]

Rockcrawler sells 15x8 x4.50 backspacing

 

[DeRocha]

For additional info take a peek at Backspacing & offset Thread.

 

[TheFox88]

Thank you guys for the help! I really appreciate you guys putting up with a retard like me.

 

[collkid]

4.5" stock backspacing... which is what i used after a 3" body lift. They stick out a little bit (15x8 wheel compared to 15x7 stock"

i was always under the impression offset/backspacing is the same thing. But according to this picture, they are indeed not

Very helpful, thanx

 

[JohnnyO]

Offset: Distance from the centerline of the rim to the mounting surface. Not sure which way is positive/negative.

Negative is when the mounting surface is closer to the back side of the rim., sticks the tire out farther. Think the deep dish rear rims on the Starsky & Hutch Torino.

Positive offset is the opposite, tire sets way inboard past the hub. Most all front wheel drive cars have positive offset wheels.