i mixed up the offset with the back spacing i though they were the same thing.

1. Is back setting the same thing as back spacing?

2. if i was a back spacing of 3.75 and they only make it in a 4 how much offset do i need?

Please members tell me what your wheel settup is if its not stock.

 

bump

 

I run 4.25 back spacing but its on a 16" wheel and i haven't really seen any on a 15 at least not yet. Also someone correct me if i am wrong but offset it the mesurement from the outside lip to the middle i think. And back spacing is the inside lip to the middle. The lower backspacing is the further it will stick out.

 

You should be fine with 3.75 or 4. It depends on what you are running tho. I am running 31-10.50-15's and am just fine with a 3.75 offset. Since I have never run with 12.50's I cant say it that offset would make tire rub.

 

offset is different then back spacing or back setting aint it cause the rims im looking and have a option of a offset of 6mm or 0mm and a back setting of 4"

so would i get a offset of 0 with a back setting of 4" I am calling it back setting becuase im not really sure if its the same as back spacing because on the manufacture spec sheet they call it back setting.

 

Did you really bump a thread twenty minutes after starting it?

 

3.75" Backspacing with 31x10.5R15 tires will cause the tires to stick out past the fender flares by about an inch. Depending on where you live, this may contradict the law and cause you to get a ticket from the police. Check your local highway traffic laws for confirmation.

Plus, having the tires and rims offset will also cause additional wear and stress on your driveline components, ultimately shortening their life span. And since they stick out past the flares, you may have clearance issues under full stuff that will require trimming of your fenders or at least larger bump stops that will limit your articulation.

 

Nice site with backspacing/offset info - https://www.rsracing.com/tech-wheel.html

 

The backspacing on my rims is 4" and the offset is -13mm. The offset is so they dont hit the brakes.

 

Alot of people say that backspace and offset are different, they really are different measurments of the same thing. Back space is measuring from the rear lip of the wheel to the mounting surface,
Offset is the measurement from the center of wheel to the mounting surface in MM's

Example 0 offset on an 8" wheel = 4" Backspace
-21 offset on 8" wheel = 3.75" backspace
This is a good page:
http://www.rimsntires.com/rt_specs.jsp

 

if you have an 8 inch rim, and the backspacing is 4, then you have 0 offset.
if you have an 8 inch rim, and the backspacing is 4.25, then you have .25 positive offset.
if you have an 8 inch rim, and the backspacing is 3.75, then you have .25 negative offset.

if you have a 10 inch rim, and the backspacing is 4.5, then you have .5 inch negative offset.

basically, the backspacing is the amount you have from the rear rim lip to the wheel mounting surface.

offset is when you divide the rim width in half (center of rim measurement) and subtract the backspace.
to the rear is negative, front is positive.

there is 25.4 mm to an inch.

generally, we don't care to worry about offset.
backspace is how much the rim will stick out past the wheel opening.

 

My mickey thompsons have 3 5/16 backspacing and a -30 offset on stock ride height and 235/75R15 tires the tires stuck out about 1-2 inches from the flares. No stuffing at all with these. Now at 3 inches and 31s the rears stuff alright but the front sets out more than the rear.

 

awww i get it know thanks guys