2015 forester tire question

Listen to your mechanic. You can do it but it is not a good idea. For one thing you will lose a lot of ground clearance and you can more easily damage the wheels on potholes.

Correct, as long as all tires are the same size the ABS will work properly. 50vs60 is not a huge difference but like stated before you are reducing clearance in suspension. The placard on the driver door wall tells you what size your vehicle should have.

You can fit it and run it if youd like, most of the stuff you can look up to figure out sizes then go out and measure it yourself. Currenly my vehicle is running tires that i was told cant fit. Measuring for myself proved otherwise. A good site for measurements is: https://tiresize.com/calculator/ As far as the tire size heres a quick break down so you know why it can fit: Tire: 225 50R17 225 = the width (in millimeters) of the tire itself (if you were looking down at the top of it) 50 = the aspec ratio, its actually a percent, based on the width of the tire and is the radius from the middle to the outer tread. R17 = rim size :P What youd more so need to be worried about when looking into tires is if you are increasing aspec ratios as it fills more of the wheel well. Lowering the aspec ratio can cause problems if you hit a really nice pot hole but most people try to avoid going 50 through those. A smaller aspec ratio takes height away (for this change it would be around .8"-1.5") so thats something to keep in mind if you offroad as i do or go over curbs occasionally. Also it could potentially increase wear as the tires would have to rotate more due to a smaller circumferance. You should easily be able to fit them as they are smaller, so its more base on if your okay with the few downsides listed. As far as rim stuff, 225 and the rim size is all youd need to worry about. R17 - R17 your good. The 225 theres actually a slight range you can work within on tires. Alot of times its more dependent on the tire (BFG/goodyear) type itself and wheel well clearance.