+18 offset *help please*

[Metal Mulisha]

When it comes to wheels, im completely lost. I am looking to run 37x12.50x20 tires on a 6 inch lift. I realize that the wheel plays an important role on if it will rub or not. The rims I am looking at are 20x9. Here is what the listing says.
Size
20 x 9
Offset
+18
Part Number
HE835
BACKSPACE
5.71"
Finish
GLOSS BLACK

Will these rub running 37x12.50?

[smotrs]

You sure about the +18? A positive offset has the wheels mounting plate closer to the outside of the wheel. This puts the wheel more tucked under the vehicle. Whereas a negative offset will shift the mounting plate closer to the inside of the wheel, moving the wheel our from under the vehicle.

I suspect you could end up really close to rubbing, but not sure. Maybe someone with a wheel that size will chime in.

Sent from my EVO using AutoGuide app.

[SickStroke6.0]

On a 9" wide wheel, you want -12mm offset (4.5" backspacing), and on a 10" wide wheel you want -24mm offset (4.5" backspacing).

Offset and backspacing are directly related..

[Metal Mulisha]

Thanks for clearing the offset up. The eBay listing says it has a 5.71" backspace. Would that make it a -18 offset? Im sure they could easily have put in the wrong offset. I haven't been able to find any with a 4.5" backspace. Closest I have found is 5.0. Would that be very prone to rubbing? That was also on a 20x9 rim.

[smotrs]

A 9in wheel with 0 offset would have a backspace of 5in. Anything greater then 5 will be a positive offset and anything less then 5 would be a negative offset. So if that wheel has a 5.71 offset, you can multiple 25.4 x .71 to figure out what the offset would be.

In other words,
5.71 - 5 = .71
25.4 x .71 = 18

So the numbers are correct for the original rim

On the new rim, if it has a 5in backspace, this would equate to a 0 offset. That's better then the previous wheel. What I don't know is whether that will clear with your year truck. I'm guessing SickStroker above has it right though with the recommendation of -12 offset or 4.5 backspace.

[Discount Tire]

Smotrs is correct, You're going to want a wheel that has a 4.5" BS. Not all wheels list their backspace. Commonly, a 20x9 with a -12mm offset has a 4.5"BS.

[93stang]

I am not running 20's I have 17x9 with 4.5 back space with 37x13.50 and dont rub at full lock.

[Metal Mulisha]

Alright thanks for the input guys. I think I found the rims I want to get. Only thing is that in order to get the 4.5 backspacing I have to get 20x10s. These wouldnt rub would they? I would probably run a 13.50 instead of a 12.50 tire.

[93stang]

Not sure if the 10's would rub, but I will tell you that the 13.50 looks alot better than a 12.50. I just switched and cant believe the differance!!!