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I want to get used Volvo alloy rims for my 1994 940 (hard to find) Apparently there is some interchangeability with the easy to find 240s as far as size and bolt pattern, but it's the offset that stumps me. According to the post I need 22-26 mm. They say some have the offset stamped in the rim but some don't. What are the reference points? I'm at a pick and pull with a tape measure where it's just row after row of rims.
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Howdy,
What are the reference points?
Take a yard stick along with your measuring tape.
Offset is the distance in inches (or millimeters) that the mounting surface is offset from the wheel center line.
Offset is related to backspacing. Backspacing is the distance from the back edge of the rim to the mounting surface.
Measure the width of the wheel rim from bead edge to bead edge; measuring the tire mounting width. Divide by 2. Keep that number in mind; that is the wheel centerline.
Lay the yardstick across the back edge of the wheel. Measure from the straightedge to the mounting surface. That is the backspacing. Subtract the smaller number from the larger number. That is your offset. If the backspacing number is smaller than the center line number, the offset is negative. If the backspacing number is larger than the center line number, it is positive.
If the wheel you want has a tire mounted, you will have to estimate backspacing as closely as you can. Lay the wheel and tire face down on ground, lay the yardstick across the tire. Measure from the yardstick to the ground. This number will be the tire width across the widest part.
Measure from the yardstick to the bead. Double that number and subtract from the tire width. Divide the remainder by 2. That is the (estimated) wheel center line.
Now measure from yardstick to the mounting surface. Subtract the distance measured from the yardstick to the bead. That is the (estimated) backspacing.
Offset is determined by subtraction just as before except using your estimated numbers.
I used "estimated" because there are all manner of errors introduced in this indirect measurement. It is close enough to make a decision about what wheel will work and which one won't; but it will probably not be exact.
--
Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)
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I say deflate the tire to 0psi and stand on the rim edge and proceed with the measurment methods given... Most pick U parts don't even charge you for the tires when you buy the rims. They consider them trash at mine - even IF they still have the "tits" on them.
2cents
Tim
--
'92 244 NOW w/ M47 (Hydra, turbo bars, bilstein, urethane bushings)
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Just look for 16 Hydras, the wheel for your car. Anyway, there are other 940 wheels but they are pretty dull looking or impossible to find. I doubt you will ever find the super-spiffy Gemini, Polaris or Galaxy, but they are all fine.
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I don't think there is any alloy wheel that came specifically on 240's that will fit on a 940 because of the big brake calipers.
You want wheels from a 740/940. Pretty much any of those 15"-16" wheels will fit. Wheels from a FWD Volvo will also fit if you invest in spacers.
-Ryan
--
Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
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Sometimes it pays to just give a rim a try. When a school teacher friend asked if I had anything to replace the bent up steel 15's on her '89 740, I had a set of BBS look alike alloy 14's w/tires that I loaned her. I was doubtful at first but they the front fine.
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True, you can get away with 14"'s on non-ABS 740's. Though once ABS came into play, you can't even get the 15" Virgo's to fit.
-Ryan
--
Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
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Really? Wow. That's one to remember. I didn't know that, though I suspected the 14" alloys would have clearance issues.
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Not sure if ABS 240's have clearance problems.
-Ryan
--
Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces, Draco Wheels
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
Buckeye Volvo Club
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They don't, but it's good to know that the 740s and 940s do.
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On the inside (backside?) there is usually an embossed or stamped symbol "ET" followed by a two-digit number -- for example, "ET20" or "ET25" -- that's the offset. Or else there's a full wheel description, such as 6.5x16x25, the last two digits being the offset.
Your 940 (if the early version), and 740's, had a 25mm offset, whereas all 240's have a 20mm offset; but this is perfectly interchangeable. I use Hydra 16x6.5 inch (offset 25mm) on my 240s.
More important, if you're considering 240 wheels, is their diameter -- many 240 wheels may not be big enough to clear your brake caliper.
Good luck.
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940 and 740 alloys are a lot easier to find than 240 alloys. Trust me, you don't want the coronas, which are the only easy-to-find 240 alloy wheel.
Any 740 or 240 rim will work fine for you, I wouldn't worry about the offset.
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