careful here. check your tyres carefully to look for ETRTO sizing. 26 x 1 1/2 IS NOT the same as 26 x 1,5. if both are decimal (or comma, depending on region) notation, great. there are several standards, they are commonly available, some seem like they'll work, but might not quite fit. That said, I use 26" x 1.25 slick tyres in the summer, 26" x 2.1 in the winter (Nokian Extreme 296) and have excellent results, note that my rims are 25mm wide, the tyres are only a hair wider than the rims. very cool looking. as long as the BSD (Bead Seat Diameter), which is the ETRTO measurement I mentioned earlier is the same, any tire will work on that rim. at the extremes, a super-narrow tire on a super-wide rim will feel relatively hard at the same pressure compared to on a narrower rim because it doesn't bulge out as much, and will not flex as "supple-y" as a wider tire would. And conversely, a very wide tire on a narrow rim might flex excessively, especially at low pressure, because it is standing on a relatively narrow base. May lead to washout in corners.