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Car Forum / Subaru Cars / December 2008speedometer recalibration - possible?
Hey all, I just got some winter tires for my 2000 outback wagon. They are a bit smaller than the stock (they are 205-55-r16 vs 225-60-R16). This causes about a 7% discrepancy in the speedometer reading as well as the odometer reading. I was wondering if anyone knew of some sort of way of recalibrating the speedometer so that it reads correctly? It's not a huge worry asI can just keep it in mind while I'm driving, but it wouldn't hurt to have it reading back to normal if possible. -Nathan In the old days of cable driven speedometers, there were mechanical adapter boxes that fit between the transmission and the cable. Local International Harvester dealers parts depts were always good source...if they didn't have the ratio you wanted, they could get it for you. Their trucks must have used those, because I could always find one close to what I needed there. More often I'd scrounge the wrecked scouts in the local parts yard to get them cheaper. I don't know what they use now that speedometers no longer have cables...and confess I haven't looked... I'd suspect that the ones IH used were SAE while the Subarus likely have metric fittings? On 12/29/08 5:33 PM, in article 3db06946-cd6f-4627-be17-58db135e0fdc@b41g2000pra.googlegroups.com, > Hey all, > [quoted text clipped - 7 lines] > > -Nathan >Hey all, > [quoted text clipped - 7 lines] > >-Nathan You don't want to have to recalibrate it again next sprong when you put the summers back on.. As far as the tire size, you went the WRONG WAY, anyways. You really wanted a set of something closer to 205 70 tires for the winter - a tad larger diameter, and NARROWER. Even better yet, something like 235 70 15 tires on 15" rims. (I didn't check the actual tire interchange for equivalencies, but it should be close and shows the direction you SHOULD be going. High profile narrow agressive snow tires on the smallest diameter rim that is available for the car - with rolling diameter either equal to or slightly larger than the factory tire. Particularly on a vehicle with anti-lock brakes. On Dec 29, 10:34 pm, cl...@snyder.on.ca wrote: > On Mon, 29 Dec 2008 14:33:31 -0800 (PST), gearjunkie > [quoted text clipped - 24 lines] > than the factory tire. > Particularly on a vehicle with anti-lock brakes. Actually, the tires he got were narrower. The 205 number is the width. He bought a tire that was 20 mm narrower. I agree that it would have been a good idea to go with a 205/70 since the extra sidewall makes them a little squishier, and thus grippier on slippery surfaces. Although, he'd still be off by about 6 or 7 percent, but in the other direction. A 235/70 would actually be wider, and much much taller. The sidewall would be 22 percent taller than the 225/60, which is way too tall. That size is typically a truck/SUV tire, so would probably be pretty heavy too. So the meagerly powered subie would then have a noticeable gearing disadvantage, and more rotational mass and unsprung weight. Not a good combination. Although the extreme gearing might help on highway fuel economy. >On Dec 29, 10:34 pm, cl...@snyder.on.ca wrote: >> On Mon, 29 Dec 2008 14:33:31 -0800 (PST), gearjunkie [quoted text clipped - 40 lines] >Not a good combination. Although the extreme gearing might help on >highway fuel economy. Like I said - I had not done the calcs - PROPER size snow tire is 215-70 15. Rolling diameter 26.85" vs stock 26.62, making the speedo error - 0.96% Or better yet a 195-75 15 (26.51 diameter. and 0.44% speedo error) The tire weight will be a bit higher, but the 15" rim is lighter, particularly if you can get a light alloy design.. Likely ballance out almost even. On Dec 30, 10:11 pm, cl...@snyder.on.ca wrote: > On Tue, 30 Dec 2008 05:08:38 -0800 (PST), weelliott > [quoted text clipped - 56 lines] > > - Show quoted text - Well, I don't want to sound like a smartass, but there are no calculations necessary to see that 205 is less than 225. The extra weight I was talking about from the 235 isn't due to the tire being larger--although that would be a contributing factor--but rather to the fact that tires in that size are made to be put on trucks and SUVs, and typically have more belts and plies and deeper tread. They are built for heavy use and therefore are heavy. I will admit that I didn't notice that you had suggested a 15 inch rim. That would help, but it wouldn't overcome the taller sidewall and heavier tire. I run 205/65 all season radials on mine, and I like the way they look and handle, but that is just my opinion. We rarely get more than 6 inches of snow here in MD, and I've been out in it with my subie with nary a worry of getting stuck. The car is very predictable in the snow. >>Hey all, >> [quoted text clipped - 20 lines] > than the factory tire. > Particularly on a vehicle with anti-lock brakes. A 235 anything R15 is a very wide tire. I agree with the 205/70 and even a 215/65. But a 235/70 would be a very large tire; assuming it even fits in the wheelwell, it would be like riding on snowshows. > Hey all, > [quoted text clipped - 7 lines] > > -Nathan If you bring it to the dealer they might be able to reprogram the ECU to accommodate the new tire size. Make sure you know how many revolutions per mile these tires are rated for. It will probably cost you the dealer's minimum diagnostic charge, and you'll have to get it reset in the spring. Bob > > Hey all, > [quoted text clipped - 14 lines] > > Bob Thanks for all the info guys. I figured it was going to be a bit of a pain to recalibrate everything since everything is electronic now, I had seen references to the gear changes other places, but it looks like a pain to change the electronics, especially if I can't do it quickly and easily. FYI, I found a site that shows you the difference in tire sizes, rotations, etc. etc. to compare if anyone is interested in how much a different size effects the speeds, etc. http://www.1010tires.com/tiresizecalculator.asp Yes, the tires I got are narrower. The first number is the width in mm, so I went from a 225 to a 205. The dealer I went to didn't have 205/65/r16s in stock (which would have been about the same diameter as my 225/60/r16s), so I went with the 55s instead. Probably should have gone a bit bigger on the diameter, but it's not too big a deal. I lost a bit of clearance (a little less than an inch), but the narrower profile will make a big difference. I guess on the bright side, I gained a little wheel well clearance. The speed difference at 70mph is about 5mph, so my speedometer will read about 5 mph high in that range. Oh well. |
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