wheel backspace help
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wheel backspace help
I'm looking for new rims and i have bushwacker fender flares to put on so i want to make sure i fill the flares out to. I was looking at 18x9 rims the first set had an +18mm offset and 5.7 backspacing the second set has +12mm offset and 5.5 backspacing is there really that big of a differnce between the two?
Lead Driver
Joined: Apr 2011
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From: Edmonton Alberta
Not sure if this will help you but....
The stock 18's and 20's are 40mm offset. You need to be a bit careful with your selection on stock suspension. I went from the stock 20 x 8 40mm offset to 20 x 9 -12mm offset with 325/60R20 tires. This puts the tires pretty much right out at the edge of the bushwacker 2" flares (even a touch past). BUT rubs HARD with stock suspension. I did have this on stock suspension for a while (because my Carli kit was late) but had to cut the front bumber bracket and bend some sheet metal at the back side of the fenders. Still rubbed when hitting bumps and turning though. There is not way it would work with the bushwacker flares thoug. +12 to +18 MAY be OK depending on what tire size you go with but you better crunch the numbers, the farther the tires stick out the closer they get to the front and back of the fenders at full lock.
I don't know how to post pics here but I could e-mail you some pics of what the 20 x 9 -12mm with 325/60R20's look like on the stock suspension but like I said, you can't have the flares unless you do some cutting.
Thanks
The stock 18's and 20's are 40mm offset. You need to be a bit careful with your selection on stock suspension. I went from the stock 20 x 8 40mm offset to 20 x 9 -12mm offset with 325/60R20 tires. This puts the tires pretty much right out at the edge of the bushwacker 2" flares (even a touch past). BUT rubs HARD with stock suspension. I did have this on stock suspension for a while (because my Carli kit was late) but had to cut the front bumber bracket and bend some sheet metal at the back side of the fenders. Still rubbed when hitting bumps and turning though. There is not way it would work with the bushwacker flares thoug. +12 to +18 MAY be OK depending on what tire size you go with but you better crunch the numbers, the farther the tires stick out the closer they get to the front and back of the fenders at full lock.
I don't know how to post pics here but I could e-mail you some pics of what the 20 x 9 -12mm with 325/60R20's look like on the stock suspension but like I said, you can't have the flares unless you do some cutting.
Thanks
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thanks for the info I'm putting a 2" leveling kit on do you think that will help with the fenders clearnce issue's you had. my email is emd160@yahoo.com if you would send pics i would greatly appericate it
Elder User
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So does +18 make the tires stick out more or less? I believe a -12 would make the tire stick way out and a +18 would be much less sticking out, correct? Will a +18 stll stick out past the stock fenders (without any flares)?
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Joined: Apr 2011
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From: Edmonton Alberta
thejean, yes basically I think that is the way it works but it also depends on the rim width. Offest is measured from the centerline of the wheel.
Based on 8" wide wheel (same as stock).
Stock = +40mm if you go to +18mm 40-18 = 22m (0.87") the tires should stick out 0.87" farther than stock.
In my case stock = +40mm going to -12mm 40+12 = 52mm (2.05") the tires stick out 2.05" farther than stock. But the rims are also 1" wider than stock so add another .5" to get 2.5". And in the real world that is about how much farther they stick out than stock.
BUT I don't 100% undertsnad how offset, inset and back space all relate so I based everything I did on rim width and offset only.
Thanks
Based on 8" wide wheel (same as stock).
Stock = +40mm if you go to +18mm 40-18 = 22m (0.87") the tires should stick out 0.87" farther than stock.
In my case stock = +40mm going to -12mm 40+12 = 52mm (2.05") the tires stick out 2.05" farther than stock. But the rims are also 1" wider than stock so add another .5" to get 2.5". And in the real world that is about how much farther they stick out than stock.
BUT I don't 100% undertsnad how offset, inset and back space all relate so I based everything I did on rim width and offset only.
Thanks
Elder User
Joined: Mar 2011
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Well, I went with 20x9 with a +18 offset today. They are installed and look fantastic! The outer edge of the tire just about lines up perfectly with the outer egdge of the bulge in the sheet metal on the stock fender, which is what I was after. 1010Tires has an offset calculator that will tell you how much farther they will protrude either inwards or outwards than the stock wheel. Great tool. And Darren, your calcs were just about spot-on! Kudos. JC
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