I see no reason to start experimenting with bigger wheels, so for tires I've been limiting my searches to my stock size of 215/60/16. Now when it comes to wheels, I understand 16" x 6.5 and 5x100, but do I need to worry about that 48 offset??
The 48 offset means that the wheel’s inside mounting plane is 48 mm outside of the center plane of the wheel. The spec is usually stated at “48 ET”, where “ET” is an acronym for “einpress tiefe
”, which is German for “offset” ("press-in depth"). The offset spec is often molded inside (or stamped on) the wheel.
allows you to change the offset and see the effect on the wheel and tire.
I gather than Impreza wheels are usually either 52 mm offset or 55 mm offset. Increasing the offset will move the wheel and tire close in to the suspension and away from the inside of the fender. For example, everything else being equal, increasing the offset from 48 mm to 55 mm will move the wheel and tire 7 mm (~0.28 inch) closer to the suspension. Using 55 mm offset wheels will reduce the car’s track by ~0.55 inches.
My 215 winter tires are mounted on 6.5 steel wheels with a 50 mm offset (from Tire Rack). Since the stock tires are 225’s on 7” rims with a 48 mm offset, the narrower winter wheels and tires have more suspension clearance than the stock tires, even with the higher offset.
And what the heck is 6.5jj
6.5jj means that the wheel nominal mounting width is 6.5 inches and uses the “jj” profile. See this site
for more info.
When I find a set of used 16" wheels, what do I really need to be concerned about other than 5x100 bolt pattern?
If the used 16” wheels’ offset is 55 mm, I’d be concerned about giving up 7 mm of clearance. Instead, I’d look around for 48 mm (preferably) or 50 mm offset wheel. Stock 16” wheels from Foresters are usually 48 mm offset. You’ll also want to make sure that you have the correct wheel center bore diameter (CB on my winter wheels is 56 mm), and the right mounting hardware (conical vs flat), but that shouldn’t be an issue if you can find some used Forester wheels. You’ll also want to determine that the used wheels are true and not bent and/or out-of-round.
Finally, should you want to consider buying new, the Firestone Winterforce
appears to be a very good but inexpensive winter tire for driving in snow. However, while I’ve not tried them, their aggressive tread pattern suggests they’ll be rough and noisy on cleared roads.
Jim / crewzer