Woods

So I made a call, and here's the deal -

This wheel is available in a 15X8 3.25 Backspacing. It weighs 20 lbs.
It is also available in an 18X8.5. Not sure of the backspacing or weight.

http://www.discounttiredirect.com/di...BMRAZ&tp=Truck

There are actually two different websites, and pricing seems to be a bit different on each. The site above is for mailorder. The local dealer network website is

www.discounttire.com

The 15" wheel seems to be right around $100.

Thanks for the info. and posting the pics!

Rubimon

The backspacing is just the distance between inside face of the wheel (where it mounts on the lug nuts) and the back edge of the wheel. Stock backspacing on the JK is 6.25". So if you are going to a tire that is a couple inches wider than the stock wheel you nead a wheel with less backspacing (or wheels spacers) to keep things from rubbing. Some people put wheel spacers on just to push their tires out a little for a wider looking stance.

Txhrns08

on there web site it says

17X8 5-127 -6AM
17X8 5-127 25AM

whats the difference?? between -6AM and 25AM ??

Jake_Blues

According to the website, they come in 3 different sizes on a 5x5" (5x127mm) bolt pattern:

15X8 5-127 -19MM (3.75" backspacing)
17X8.5 5-127 -6MM (4.5" backspacing)
18X8.5 5-127 -6MM (4.5" backspacing)


-E

Rubimon

Be careful, some 15" wheels will fit others may not.( Might be tight around the disc brake caliper) That is the danger of ordering them mail order as it might be nice to be able to try them. If you got 16's you'ld be okay for sure. Email the guy on this site who has them and ask him what size he has and if there is enough room to do a 15" wheel of the same style.

Rubimon

I would also call the manufacturer, sometimes they have the size you want but websites may not have been updated. That was the case with mine.

Jake_Blues

The -6 or 25 is the wheel offset in millimeters. There are 25.4 mm to an inch. Zero offset would be right in the middle of the wheel, meaning the wheel mounting surface is exactly on the centerline of the wheel. Negative offset means the wheel mounting surface is closer to the INSIDE rim of the wheel which creates MORE backspacing (more wheel on the outside than the inside). Positive offset means the wheel mounting surface is closer to the outside rim, creating LESS backspacing (more wheel on the inside than the outside).

For a -6mm (about 1/4" negative) offset on an 8 inch wide wheel, your backspacing would be about 4 1/4".

For a 25mm (about 1" positive) offset on an 8 inch wide wheel, your backspacing would be about 5 1/2".

The formula to figure this out is:

(Wheel Width / 2) + Offset = Backspacing

If you're following my math you might argue that the above numbers are wrong, but one thing you need to remember is that the advertised wheel width is actually measured from the inside of one rim to the other. However, backspacing uses the actual width of the wheel from the OUTSIDE of one rim to the other, so you need to add about half an inch for the width of each rim.

Thus, to use the example above for a 17x8" wheel with a 25mm (1") offset:

(9" / 2) +1 = 5.5"

And you thought Algebra would never come into play in off-roading!

-E

Woods

Great point. There is a local dealer about two miles from my house. I'm going to ask about the 15" on a JK, but just like Jeep dealers, I won't trust his opinion. Point being, I'd have them install a wheel to check clearance prior to buying. I don't think that the guy who posted the pic, is a forum member, so no go on the email. From the looks of the pic, I'm guessing that those are not 15's though.

BTW, My JK is still on order, so I'm just going to the wheel dealer to look.

Txhrns08

thanks jake_blues that helps alot but one more newbe question

the less that back space the farther the wheel will stick out, also allowing a slightly bigger tire?

am i right??

for expample 5 1/2 in back spacing sets the wheels farther under the jeep than 4 1/2 in. does?

Jake_Blues

For the most part that's true, if you're talking about the same width of wheel in both cases. It gets confusing when people start comparing the backspacing of different width wheels. The offset is really what you need to worry about, because this determines where the TIRE will be.

For example, a 10" wide wheel with a -25mm offset will have a backspacing of 4.5". An 8" wide wheel with a 0 offset will also have a 4.5" backspacing. However, if you put a 12.5 inch wide tire on both of these wheels, since the centerline of the 8" wheel is 25mm (1 inch) closer to the vehicle than the 10" wheel with the same backspacing, your TIRE might rub even thought the WHEELS won't. Hopefully I made that clear.

You also still have to make sure that when you stuff the front tire up, it clears the inside of the fender. So there is a practical limit as to how far you can push the tire out to clear wider meats.

Also, everyone measures these things a little differently so when you start getting close to the limits of what will fit, the only way to really know is to try it.

-E