I just bought my 8 a week ago and we've had a snow storm already.

I got some used Maxda 3 17" but I am unusre whether to go 215/50/17 or 215/55/17

I know smaller is better, but it seems that most of you here get 215/55/17 for a winter setup. any specific reason?

thanks

The simplest reason for choosing a 215/55/17 over a 215/50/17 is that the former is closest to the stock rolling diameter on a 225/45/18 set up, so you get the least speedometer error.

The 55 series would come in at 26.3" diameter, compared to 26.0" stock, which will give about a 1.3% too slow error on the speedometer.

The 50 series is 25.5", or 2.0% too fast error on the speedometer.

In winter, you want a slighter higher sidewall and ride height to get you some extra ground clearance - it also helps soften the ride a bit on rough, chewed up roads.

I have 215/55/17 on mazda3 17's
I wanted the biggest sidewall for ride quality reasons

so far so good