Tire Sizes supported by Tis2000 for 2000 SIlverado

I'm considering moving to a slightly wider tire on my 2000 1/2 ton silverado extended cab w/towing package. Right now I've got 255/70R16s
which really seem to be an odd size compared to the Tahoes and even newer trucks. The 265/75R16 seem to be a popular size plus would give me the larger contact patch I'd like. When I change, the sidewall size will change throwing off the speedo. I found a pdf from GM talking about having to reprogram the PCM with the TIS 2000, but that only certain tire sizes are OK for certain vins. Anyone have access to a TIS 2000? What the hell is a TIS 2000? I don't want to buy tires and then find out I can't correct the speedo/odo. thanks Chris
(below are the steps from the pdf I found) http://service.gm.com/gmtechlink/arcv_pdf/2_00_e.pdf
Although GM recommends that replacement tires match the OEM tires, it is possible to install tires that match factory optional tires for the vehicle in question. If this is done, it may be necessary to reprogram the vehicle's PCM to recognize the size of the tire installed (remember, the rolling radius may vary on tires of different sizes). Reprogramming for this purpose is not chargeable to warranty; the dealer must obtain any required reimbursement from the customer. Here's how to determine which tires are supported for a particular VIN: - In TIS 2000, select SPS. - Select Information Only. - Enter the VIN. - Click Next. - Select PCM/VCM. - Select the Reconfigure box. - Click Next. - The tire size chart will appear.
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I do have access to tis at work, as long as you keep the tire diameter or radius the same, you do not have to reflash anything.... there are sites that have tire "rolling height" specs... If they are different, or if you want to see what you can change, get me the last eight of your vin, and I can check monday what's available for you.. Bobo

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If you have 255/70R16 and plan to go to 265/75R16 I'll tell you right now that the tires will be taller and narrower then what you have. Not wider! To correct the Speedo being out, though by not a whole lot, get a Hypertech Power Programmer. You'll then be able to correct the problem. All I can say is go to a tire shop and put the 2 tire sizes side by side. 255/70R16 is a common tire size these days. If you want a wider contact patch, the second number going smaller will give you a wider tire. For Example, I have 20x8" wheels on my truck. The tires I have on it are P275/45R20. Now Ignoring the 20, (I think I used to have the 255/70R16's on my 03 Silverado also) going with a Larger first Number, and a Smaller Second Number, allows the Tire to stay about the same hight(Same Diameter), but get a lot wider. Of course having 20's makes the sidewall a whole lot smaller then from the 16's that were on it. It's called Upsizing. Wheel gets larger, and the sidewall gets smaller, but the overall Diameter remains the same so no calibration required.
If your looking for WIDER, you need to look into something like a 60 series tire. If you can find something like a 285/60R16 or something round there, the over all Diameter would remain the same and the tire would be quite a bit wider. If you used a 255/60R16 The tire would be Wider, but the height would end up shorter. I don't have a tire catalog here so I don't know if they make such a size or not. Of course a 60 series tire on a stock wheel will look a but funny, but at least you would be less likely to go curbing your wheels.
If you went with a 265/70R16 not a 75 series, then the tire would be a little taller and a little wider then what you have not. It wouldn't be very much though. Not enough to worry about the Speedo. It wouldn't really be worth it unless you NEED tires now.

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On Sun, 11 Jan 2004 12:40:04 -0800, "JBDragon"

they'll be taller AND wider... section width of 265 MM and a sidewall height of 198.75mm (265*75%). a 255 will have a section width of 255mm and a sidewall height of 178.5mm (255*70%). there is no way going to a larger section width will result in a narrower tire.
the following are BFG AT/KO's as listed at www.bfgoodrichtires.com
LT265/75R16/D
tread width: 10.5 on 7.5
Overall height: 31.8
LT255/70R16/D
tread width 10.2 on 7.5
overall height 30.2
-Bret

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JBDragon, I appreciate you trying to help, but I think you are way, way off. 265/75 is bigger in width and height than 255/70. The first number is the width of the tire in mm's, and the next is for the sidewall calculation-- essentially the % of the width that equals sidewall height. Therefore the 265 is wider by 10mm than the 255 and by virtue of 265x75% being bigger than 255x70%, is also taller.
http://www.tirerack.com/tires/tiretech/general/size_information.html

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Was thinking of switching tires also. BFGoodrich TA's come in a large size very close in diameter to 255/70-16 ( 30.5 inches I think)but they do not have as high a load rating. Was thinking of getting these but not sure of the load ratings.

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