[MacAttack]

I need some winter tires, and I've found that the tires I have on aren't in tire rack anymore. I've also had a hard time getting 235/45-17 winter tires. They're wider than I'd like, but it's the closest fit to stock size.
Any other sizes fit well? I'm thinking maybe 225/45-17, a slightly more narrow tire, but also smaller than the stock tire by more than my current winters (-1.7% vs -0.3%). It also has more tire options. Is the difference small enough, or should I suck it up and stick with the 235s?

 

[MacAttack]

215/50-17 is recommended by TireRack, but that's a 4% difference. I'm thinking 215/45-17. It's only +0.6%. This gives me a number of good options as well, and it's 2cm more narrow than stock, with more rubber to absorb the impact of hard ice or packed snow. Good plan, or am I missing something?

 

[ajcomputer]

Well, I don't have any scientific data to back it up, but I've always had the understanding that narrower tires are better for snow as there is less area for the tire to dig through to get to pavement.

 

[MacAttack]

Well, I don't have any scientific data to back it up, but I've always had the understanding that narrower tires are better for snow as there is less area for the tire to dig through to get to pavement.

Agreed. I was more concerned about going too narrow with the tire, and potentially "stretching" it over the 8" wheel, something I refuse to do.

 

[dgc333]

215/50-17 is the stock 17" Focus size. For all practical purposes they have the same outside diameter as the ST's 235/40-18 tires (25.5 verse 25.4").

 

[dgc333]

215/50-17 is recommended by TireRack, but that's a 4% difference. I'm thinking 215/45-17. It's only +0.6%. This gives me a number of good options as well, and it's 2cm more narrow than stock, with more rubber to absorb the impact of hard ice or packed snow. Good plan, or am I missing something?

The stock 235/40-18 is 25.4" in diameter.
A 215/50-17 is 25.5" in diameter. This is the stock optional 17" Focus size.
A 215/45-17 is 24.6" in diameter.
A 225/45-17 is 25" in diameter.

The 215/50-17 is the closest to the stock size and is only 0.4% larger. While the 215/45-17 is 3.1% smaller. A 225/45-17 is 2% smaller in diameter.

If you have 7" wide rims a 215/50-17 is perfect. Closest in diameter to the stock tire and 7" rim is right in the middle of the recomended rim width.

 

[MacAttack]

The stock 235/40-18 is 25.4" in diameter.
A 215/50-17 is 25.5" in diameter. This is the stock optional 17" Focus size.
A 215/45-17 is 24.6" in diameter.
A 225/45-17 is 25" in diameter.

The 215/50-17 is the closest to the stock size and is only 0.4% larger. While the 215/45-17 is 3.1% smaller. A 225/45-17 is 2% smaller in diameter.

If you have 7" wide rims a 215/50-17 is perfect. Closest in diameter to the stock tire and 7" rim is right in the middle of the recomended rim width.

They're 8" rims. I know I should have gone with a thinner rim for my winter wheels, but I really loved those wheels. It seemed like 215/45-17 was closer to the stock (I used an online calculator to come to that conclusion).

 

[MacAttack]

For the record I went with Goodyear Ultra Grip Ice WRT, 215/50-17.

 

[dgc333]

They're 8" rims. I know I should have gone with a thinner rim for my winter wheels, but I really loved those wheels. It seemed like 215/45-17 was closer to the stock (I used an online calculator to come to that conclusion).

You aught to update the subject of your post then. It's says 17x7. If it is that important to you to not put the tire on a rim .5" wider than recomended then then the closest tire to stock in diameter that fits a 8" rim is 225/45-17. It is 25" in diameter verse the stock 25.4"

I have 2w5/50-17 winter tires on my ST. They are a little larger in diameter than the a 45 series, I wanted more side wall.

They're 8" rims. I know I should have gone with a thinner rim for my winter wheels, but I really loved those wheels. It seemed like 215/45-17 was closer to the stock (I used an online calculator to come to that conclusion).

 

[MK3 ST3]

http://www.fordservicecontent.com/Ford_Content/catalog/owner_guides/13focst1e.pdf

215/50-17 is the size you want if you go thin. Otherwise get 235/45-17 (which are hard to find). Both are listed in the Owner's Manual (linked above) under "Winter Tires." Tire Rack used to list the wrong size (it seems to be correct now).

BTW the Section Width of a 215/50 is only .79" less than the 235/45.

 

[evoray]

I'm currently running 215/50/17 General Altimax winter tires on 17x7.5" rims and they look/feel/drive fine on cold, dry roads. We shall see how they do once snow and ice happen. Should be fine though. I run the same tires on my Evo but at 235/45/17 on the oem 17x8" rims.