Hello Bebelacus. You can definitely use narrower tires on the same 17" rims, but your aspect ratio will have to change to keep the overall diameter similar. Also, you will have to keep in mind the load index or maximum load rating for the skinnier tire versus the stock tire will probably be lower. Once you find a tire you want, you can check that tire on the manufacturer's website to see what rim width range is specified and what the load rating is. Usually, 205 or 215 tires can be fitted to 6-7.5" rims. So, you could theoretically get a 205/70R17 or 215/70R17 tire to use on the stock 17" rim (since it is 7" wide) and they would probably fit, but there aren't a lot of choices in those sizes, perhaps only a handful. For example, the Blizzak DM-V1, a good winter tire, comes in 215/70R17, uses a 6.5-7.5" rim, but has a 100 Load index versus a 102 Load index for the stock 225/65R17 tire. Technically, you can't load your CX-5 as much with cargo and people with a lower load index rating, but this only comes into play when you are loading the CX-5 to its absolute maximum weight/cargo capacity and at that point, the lower load index can potentially affect ride safety. However, if you are looking at skinnier tires for the winter, that is a good idea as skinnier tires cut through snow better, like a skinnier or sharper blade cuts better than a fatter or more dull blade.