: Help!!! Awd question.

11-30-10, 05:44 PM
I am looking into getting snow tires and am wondering if I can get all four the same size tire? My stock is 255-45-18 rear and 235-50-18 front. I found a good deal on a set of four 245-45-18. Has anyone done this? thanks


11-30-10, 08:49 PM
It's an open differential. Although some feel otherwise, I'm confident you won't have a problem with the same tire on all four wheels. I have Conti DWS P235/50R18's all around and run the backs 1-2 PSI lower than the fronts. The AWD is more forgiving of poor traction than the RWD models; where are you,? You may not really need snow tires.

I thought about P255/45-18's but opted for a softer ride. Wider tires will also be less effective in snow. The 245's you thinking about are slightly smaller in diameter so your speedometer will read a bit high. If you don't mind that, you should be OK.

11-30-10, 11:49 PM
Hi, I am in north dakota and it's my wifes car so I want to put blizzaks on it. I even have them on her subaru that is very good already with factory tires. It is dumb because I've called all the cadillac dealers within a 150 mile radius of here and they all say different. I got answers ranging from it's fine to don't do it all and yet the best one........this is bad.......one place the service guy told me they are supposed to be all the same from the factory. I told him my car and the current sizes and he said "nope, they should all be the same"!!! Also EChas3 did you mean open transfercase or differential? I am most concerned about the transfer case with front vs. rear from factory is different diameter. thanks


12-01-10, 12:34 AM
I have had the same size Blizzaks all the way around on my AWD V8 STS every winter since I bought it and have never had any trouble.

12-01-10, 10:30 PM
Front, rear and transfer case are all open differentials on the AWD STS. Traction control does the rest by applying braking to slipping wheels. Forum members report all sorts of weird statements from dealers. I think it's fair to conclude that most are ignorant.

My car came with 235/50R18 Front and 255/45R18 Rear and the previous owner's dealer rotated them with no evident harm. The tires were reversed when I took possesion of the car and I had no issues (but did get the selling dealer to make things right). Those tires are almost exactly the same circumference.

I'd wager the AWD's with 17" wheels are likewise so close as to be identical.