What are my options for replacing tires for 2001 Subaru Outback? One tire is damaged and it seems I need 4 matching tires as it is AWD. 255,225,260,...etc. If they match, can I change size?
If they match, can I change size?
tl;dr: only slightly unless you also change your wheels.
I generally start with Tire Rack's excellent tire database:
For that vehicle, you're looking at 225/60-16 (and they list 43 tires in that size right now). It is possible to adjust those two first numbers slightly but it's usually not worth it.
The first number is the width of the tire: too much bigger and it will rub the fender lining and look ridiculous. Too much smaller and it will run the risk of falling off the wheels as the bead won't seat. The second number is the aspect ratio of the tire (sidewall height : tire width). Smaller numbers equal flatter tires while larger are rounder.
Either will affect the speedometer reading (so you have to adjust the first two numbers together if you'd like your speedo to read properly). Here are some reasonable matches for "plus zero" sizes:
Side Diam Diff wall (mm) (mm) (%) 165/80R16 132 670 -2.22 175/75R16 131 669 -2.78 185/75R16 139 684 2.78 205/65R16 133 673 -1.30 215/65R16 140 686 3.52 245/55R16 135 676 -0.19 255/55R16 140 687 3.89 265/50R16 133 671 -1.85
As you can see from that last column, there's going to be an effect on your speedo reading no matter what. Some of the sizes are pretty close, though: 245/55-16 is an inch wider than the original equipment size and works out to a closer diameter. However, I wouldn't be surprised if that extra inch resulted in rubbing the fender liners on a bump.
The final number indicates the diameter of the wheel that it's going on. That has to match. There's no sensible way to put a 15 inch tire on a 16 inch wheel.
I wouldn't change the size. It screws everything up.
Speedometer, ABS, transmission....all of the sensors think the car is going a different speed than the actual speed.
I haven't done it but I would say that the ensuing results of changing the outside diameter of the tires would not be desirable.
This question is closely related to: difference between 175/70R 13 and 155 R 13 tyres
According to my reply on the post above (and @Paulster2 comment), you COULD change the tyres. You are talking only about the width of the tyre. For FWD or RWD cars: as long as the two on the front match with eachother and the two on the back match with eachother, you're good. But in a 4x4, permanent AWD/4WD you're better off to choose 4 matching tyres for your car to maintain equal grip on all wheels.