Wheel Gurus in here, backspace help on an 11" wheel...
07-14-10, 06:57 PM
#1
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Wheel Gurus in here, backspace help on an 11" wheel...
Ok so I have 10.5" on the car now with a +27 backspace and I'm happy with how it sits, what I need to figure out is what I would need backspace on an 11" wheel to keep it sitting the same in accordance to the fender, in other words I want the wheel to go in towards the frame 1/2 an inch. I'm not trying to do anything special at all, I just want to retain whats there now and move up the width of the wheel and have it grow inwards not outwards. I'm having the wheels made so offset isnt a problem, I can get anything from a +13 to a +44, any help is greatly appreciated.
07-14-10, 08:45 PM
#5
Someone explained this to me before but I forgot how to explain it in detail, so here is my attempt. Basically, there are 25mm in an 1", so for 1/2", in theory it should be 12.5mm, but for some reason, when you truly measure it out, it's really about 6mm or 7mm. So, if you have now 10.5" +27, that would be equivalent to how a 11" +34 wheel would sit, or 11.5" +41. Going the other way, it would be equivalent to 10" +20. Does this make sense?
07-15-10, 01:11 AM
#6
Keep in mind, the reason it's only 6-7mm is because the wheel widens from both sides. It doesn't just widen on the inside face of the barrel 
. So increasing wheel width by 12.5mm translates to increasing 6.25mm on each side(inside/outside faces) of the wheel. Thus, you only need to add 6.25mm to the offset to keep the wheels sitting at the same location as before 
. So increasing wheel width by 12.5mm translates to increasing 6.25mm on each side(inside/outside faces) of the wheel. Thus, you only need to add 6.25mm to the offset to keep the wheels sitting at the same location as before
07-15-10, 09:19 AM
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Keep in mind, the reason it's only 6-7mm is because the wheel widens from both sides. It doesn't just widen on the inside face of the barrel . So increasing wheel width by 12.5mm translates to increasing 6.25mm on each side(inside/outside faces) of the wheel. Thus, you only need to add 6.25mm to the offset to keep the wheels sitting at the same location as before
. So increasing wheel width by 12.5mm translates to increasing 6.25mm on each side(inside/outside faces) of the wheel. Thus, you only need to add 6.25mm to the offset to keep the wheels sitting at the same location as before Trending Topics
07-15-10, 09:30 PM
#8
Keep in mind, the reason it's only 6-7mm is because the wheel widens from both sides. It doesn't just widen on the inside face of the barrel . So increasing wheel width by 12.5mm translates to increasing 6.25mm on each side(inside/outside faces) of the wheel. Thus, you only need to add 6.25mm to the offset to keep the wheels sitting at the same location as before
. So increasing wheel width by 12.5mm translates to increasing 6.25mm on each side(inside/outside faces) of the wheel. Thus, you only need to add 6.25mm to the offset to keep the wheels sitting at the same location as before 
I think it might have been you that explained it to me originally Jeff.
07-15-10, 11:12 PM
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I was completely wrong about my wheel and offset, it's actually a 10 with a +42, so that being said I'm guessing I need to be around a +52 if I want to fit a 305/30/20 on an 11.
07-16-10, 10:16 AM
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It's going to be around 6-700. I know I've seen a couple guys on here with 11's. Tturbopimp and bluelex have them.
07-16-10, 10:55 AM
#15
My GS has a 20 X 11 at +45 offset. I run a 305/25/20 and have essentially no gap ( dropped ~ 2 inches ). With this set-up you will need to shave the fenders to avoid rub, unless you're running massive camber. A 305/30 is going to be a tall tire and I would expect rubbing.