Wheel offset for 75-91 model years
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Wheel offset for 75-91 model years
Does anyone have any experience installing larger rims and tires on these older models. Mine is a 1989 E250 and I want to install 18"x9" rims while keeping the tires from protruding from the wheel wells too far. My biggest concern is having the rims clear the brakes and suspension. I have read that I should keep the backspacing to around 4" however most wheel manufactures only list offset. Can anyone give some advice. Thanks.
Hotshot
Joined: May 2003
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From: south louisiana
Take a wheel off, lay it flat, upside down, then with a tape measure and a straight edge laid across the rim, measure from the surface of the wheel that contacts the axle flange to the straight edge, this will give you the backspace. Going to 18" wheels, you're not going to have any worries about interfering with the brakes at all. Increasing the backspace, you will move the inside edge of the tires closer to the suspension, but generally, you already have a good bit of room to play with here. Measuring the clearance you have now will give you a good idea as to how far in you can move in increasing the backspace with different wheels. If the difference is in fractions of an inch (less than 1") there should be no worries. If it's in more than an inch or two, then chance are you will have problems
Postmaster
Joined: Feb 2011
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when i put 19.5 wheels on my e350, i had no problems except needing to hammer on the sheet metal at the rear of the wheelwell to gain the needed clearance for the outer edge of my tires when turning. thats with skinny tires - 225/70r19.5 - 32" overall.
i believe offset is defined as how far off-center the mounting surface is - so for a 9" wide wheel, a 4.5" backspacing would be zero offset.
having too much backspacing will result in your tires rubbing on the suspension arms when steering too tightly - and this problem can often be found with wider tires on stock rims, so you don't have too much room to play with if you want to keep your full steering range.
i believe offset is defined as how far off-center the mounting surface is - so for a 9" wide wheel, a 4.5" backspacing would be zero offset.
having too much backspacing will result in your tires rubbing on the suspension arms when steering too tightly - and this problem can often be found with wider tires on stock rims, so you don't have too much room to play with if you want to keep your full steering range.
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