View Full Version : 06 STS Tire Size Rim Width Compatability and rim size change ABS recalibrate.

03-15-11, 03:12 AM
Ok, so I dented a rim on the front left just enough to where the tire wont hold air from a pot hole. The dealer is asking too much for a new rim and I don't really want a single new rim and 3 with normal wear and it was almost time for new tires anyway. So I decided to use the chance to step up to 19" from the stock 18" and to reinstal the TPMS that some jacka** was kind enough to remove when puting on the last set of tires.

The recommended tire size for my car as per cadillac is 235/50ZR18 Front and 255/45ZR18 Rear. When ordering the TPMS from the dealer informing him of my dilema they brought up some issues about changing rim sizes and how it affects the ABS and that you have to get it recalibrated if that model of car can even be done? (apparently some cant be recal)

So I found the rims I want with keeping in mind I wanted rims to be on all year and I live in NE Ohio, plus I didnt want to compromise the ride by that much if any. http://www.wheelsnext.com/wheels-rims/TSW-Snetterton-Hypersilver.html
The 19" rims are only 8" wide and one of the issues I am facing is that I want to run 255/40ZR19 on the rear but none of the tires that size say they will fit a rim as small as 8" wide and recommend size is 8.5"-10". Is it possible to fit those tires on the rim safely or will the tire place even consider doing it? The 235/45ZR19 Front fit 8" rim and they do have a 245/40ZR19 that will fit the 8" but I would like to keep the 255 on the rear as I need all the extra help I can get in the heavy snow that my area gets.

Also if I have a none dealership place install the TPMS when putting the tires on is there anything I need to have them do so that I can calibrate it myself? I've read how to do it and it didnt seem overly complicated to where I feel I need to pay 40-50$ for someone else to do it.

03-15-11, 05:45 AM
The ABS and Stabilitrak doesn't care how wide your tires are, it cares what the diameter of the tire is. If you replace wheel sizes you have to match the overall diameter (so the computer can calculate how far it is going with tire rotation). You mention that you don't want to compromise ride, well then, you should probably want to stay with the same diameter wheel (though a one inch probably wouldn't reduce ride quality much). However your logic on snow control actually gets worse with wider tires, so again, the 18's would be better than the wider 19's (here again, not by much).

03-15-11, 07:23 AM
The 19X8 aren't wider than my stock 18X8 and im hoping 18->19 wont comproise it by "much". Also I used some silly tire size calculator and because i went down on the side wall size on each tire and up only an inch that they might be within the limits of the change allowed I think. The dealer said something like .5 difference allowed.

235/50/18-> 235/45/19 Front
255/45/18-> 255/40/19 Rear
This site says to stay within 3% or you can suffer brake failure and its way within limits by that.

03-15-11, 07:54 AM
So narrower tires are better for snow dammit it's either better snow traction and not as good summer traction. Or nope that the tires I want do better in the snow then the ones I have. :/