"fat tyres"

[27x1.4]

I hope I am in the correct forum - "fat tyres"!
Will a 26x1.75 tyre fit a 26x2.10 rim?

Now before you laugh, I do not own a mountain bike (this is for a friend) and I have always had the same size road wheels hence the choice of user name.

 

[alfeng]

Will a 26x1.75 tyre fit a 26x2.10 rim?

There are actually several different 26" size rims! You have to check the ERTO on the existing tyre & the new tyre.

Otherwise, you should be "okay" putting the narrower tyre on the current rim which is hopefully a 559x17, a 559x22, or something in between.

 

[alfeng]

BTW. You'll probably need to use different tubes for the two different tyre sizes.