Wheel offset question

[Jeepinjosh4.0]

I’m currently using a wheel with a -38 offset with a 4 inch backspace

I’m looking at a set of rims with a -43 Offset and 3.750 inches of backspace.

Can anyone give me a general idea of how much further out of the wheelwell the new ones would stick out compared to my current setup?

 

[Mike_H]

.25 inches

 

[Pokey02]

I’m currently using a wheel with a -38 offset with a 4 inch backspace

I’m looking at a set of rims with a -43 Offset and 3.750 inches of backspace.

Can anyone give me a general idea of how much further out of the wheelwell the new ones would stick out compared to my current setup?

Offset and backspace describe the same thing, they are just expressed differently. That's why the answer is .25

Sent from my SM-G955U using Tapatalk

 

[Mike_H]

Offset and backspace describe the same thing, they are just expressed differently. That's why the answer is .25

Sent from my SM-G955U using Tapatalk

Not exactly... but close. Offset is measured from the middle of the rim to the mounting surface. Backspace is the physical edge of the wheel to the mounting surface. So... on an 8 inch wide wheel, you'd think a 3.75 backspace would be a -6 offset, right (6mm being approximately 1/4 inch). It's not...3.75 backspace on a 8" wide wheel is -19.

Here is why... rim width is measured to the tire mounting surface, which is inside the outer lip is the rim. Backspace refers the outside of the outer lip. So... to find the middle, you basically need to add an inch to the stated rim width. Again, with an 8" wide wheel, plus 1 inch to account for inside to outside measurement, we have 9 inches. Divided in half, means the center is at 4.5 inches. Now... we take 3/4 off an inch away (19 mm) and what does that leave? 3.75" backspace.

Convoluted, I know.

 

[billiebob]

43-38=5mm... or
4.00-3.75=0.25".