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Discussion Starter · #1 ·
Could someone help me determine which size tires I would need for a 19x8 rim and a 20x9.5. I'd prefer to have the same sidewall height on both tires.

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Mike S.
94 BBB SS - 96 DCM SS - 92 BBB Wagon - Iowa SS - HERD
www.marshallnet.com/sogge/impala/
 
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Discussion Starter · #2 ·
Are these for one of your SS's or the wagon?

Or you can just check this out: http://www.dsm.org/tools/tiresize.htm

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Cheston P - AIM:Impalaitis
96 BBB Impala SS "ADIOSS": best [email protected] (!)homeplate, swiSS-cheesed airbox, blue bowtie, GT front rotors, PF pads, MOOG'd, clear corners, many SEO options, dual trunk lights, Mobil1 oilcap, C5 croSSed flags, throttle-body bypaSS...
91 white Caprice 'n0n 9C1' w/L03: best [email protected] custom glasspack exhaust, opened up airbox, MaCo Motorsports billet grille, (!)antenna hole, (!)hubcaps, limo tint, Pioneer/JBL/BOSS/Kicker equipped stereo, LTZ hood badge, black rear bowtie...

[This message has been edited by AdioSS (edited September 05, 2000).]
 
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Discussion Starter · #3 ·
These would be for the wagon.

I also assume I'd need a different reluctor for the differential to make the computer think it has the same height of tires. It currently has a stock 3.23, so which reluctor would be required (if one was)? What about reprogramming the speedo?

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Mike S.
94 BBB SS - 96 DCM SS - 92 BBB Wagon - Iowa SS - HERD
www.marshallnet.com/sogge/impala/
 
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Discussion Starter · #4 ·
2Imps,

Unless you're changing gear ratios when you change tires, you don't need a new abs reluctor. Just get as close as possible on tire diameter (f and r) and you'll be OK.

Also, unless you absolutely want to, you don't need to reprogram for the different tire size. If you get real close to stock size, your speedo & odo won't be far off. Check out this link...
http://www.miata.net/garage/tirecalc.html
It will tell you what % your speedo will be off. HTH.

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Scott VacaHeart of Texas Super Sports
95 DGGM --- Best ET: 14.21 @ 98.12
Check it out… www.HOTSS.com/Members/scott_vaca/4DR-VET.htm
[email protected]
 
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Discussion Starter · #5 ·
I'm guessing your stock tires are somewhere between 215/75 and 235/70, right? That's on a 7 inch wide rim. Since you'll be stepping up an inch in the front and 2.5 in the back, wider tires will be needed.

You can find 245/35ZR-19 that should work for the front. And 285/30ZR-20 that should work for the rear. You can find a few tire manufactures that make these sizes and other sizes that are very close at Tirerack.com Prices there range from about $250-330 for the fronts, and $330-400 for the rear. Personally, I'd recommend using the same type of tire for the front and rear.
 
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Discussion Starter · #6 ·
Right now, the car has 255/50 17" Potenza RE730's on OEM aluminum Impala rims. The tires would be different heights from each other, which I assume would cause the ABS to go wacky due to the different # of rotations. This is why I was thinking I would need a different reluctor to fool the PCM into thinking it had the same size tires. Is there a way to program the '92 computer into thinking they are the same? Who/what can do this?

Boy, this really shows my lack of experience with weird tire sizes.

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Mike S.
94 BBB SS - 96 DCM SS - 92 BBB Wagon - Iowa SS - HERD
www.marshallnet.com/sogge/impala/
 
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Discussion Starter · #7 ·
It IS possible to get the different size tires to have a very similar overall diameter. Using some algebra
just figure out the size that you need. Unless you have had the computer reprogrammed, it would probably be best to try to stay close to the diameter of the stock tires that came on the wagon. Then your ABS shouldn't be bothered by the difference.
 
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Discussion Starter · #8 ·
Why exactly do you have to have same diameter (or close too) on front and rear... An ABS thing I've heard, but hwat is the reasoning???
 
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Discussion Starter · #9 ·
Time to clear things up


You have to have the same size tires F and R because the ABS system uses wheel speed sensors that EXPECT you to have the same diameter tires. There is a little "slop" allowed (few %), but not much. If you have significantly different diameter tires F and R, the ABS will freak out and turn on the ABS light (not to mention won't function as effectively, if at all).

As for the "different diameter" trick : I did the math a while back and figured out some exact tire sizes you could run along with a ABS reluctor trick (3.42 reluctor on 3.73 gears) that would keep the ABS happy. However, it was on the small size tire-wise in front, and BIG (i.e. tall) in back. It'd work at the dragstrip, but look goofy as hell on the street


So twoimps : go with the same diameter tire F&R. Your 92 ABS system, for all intents, is identical to the 94-96 SS ABS. You might also wanna re-think the 19s : it's actually cheaper (at least on tires) to do 20s.

Ed
 
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Discussion Starter · #10 ·
I'm wanting to do this for the appearence. Cost isn't really a factor here as they won't get a miles put on them very often once the car is customized. If 19's won't/don't work, I'd go with 18's. Some how disabling or removing (gasp!) the ABS if I can't do the reluctor.

I've seen a wagon in person with 17's and 20's that looked good, but would have been better with larger diameter rims in the front. Don't know what they did about the ABS though.

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Mike S.
94 BBB SS - 96 DCM SS - 92 BBB Wagon - Iowa SS - HERD
www.marshallnet.com/sogge/impala/
 
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