What's the smallest diameter tire I can put on a 26" MTB rim? The rim says 559x17. Does "17" mean the rim width is 17mm?
I typically road bike, but I have an older Rockhopper that I would like to use to pull my kid around in his trailer. It currently has really knobby 26x1.95 tires that have a lot of road resistance. I'd like to replace those tires with a smaller, smoother tire.
Find the ETRTO number on the rim (not the one on the tire). It should be 559 x XX. There is a page on Sheldon's site that will tell you what size tires you can use.
The OP says the rim is marked 559 x 17. That is on the narrow end of the spectrum for a mtb rim, but I do have a couple of mtb wheelsets with rims of that width (measured between the two inside walls of the rims). I've run anything from 26" x 1.0" to 26" x 2.14" tires on them, no problems. So to answer the question, "how narrow a tire can I use?", the answer is as narrow as you want for a 26" mountain bike tire, which as far as I know don't come any narrower than 1.0 inch.
Thanks for the help. I found the link to Sheldon's site regarding tire sizing. My wife has a hybrid with 1.25" tires. I didn't know if I could even go that low of diameter. I went with some 1.5" street tires that should serve me well.