How to check to see the maximum tire size to fit your bike
Doesn't matter make or model.
If you are going to try and switch to a wider tire or a little taller tire then you have now , and want to see if it will fit without mods try this.
Buy some kids modeling clay (dollar-tree $1.).
Roll out a 1" thick (hotdog shape) piece , about 12 " long and press it to your tire from rim to rim, tape if necessary.
Get on your bike, and your wife on the back and roll the bike back and forth , make sure you don't run over the clay.
Then get off the bike and look where the clay is dented or scraped and measure the height from the tire to the thinnest part of the clay.
Again both of you get back on and roll the bike so the clay is at the point of closest contact and jump up and down.
Then check again to see if the clay is distorted and measure the height from the tire to the thinnest part of the clay.
Lets say that you have 25"tall tire and the dent on the clay is at the top of the tire and is just over 1/2" thick, and you double it (top and bottom) and you now can go 1" taller , or a 26" tall tire.
But if you have a tire 6"wide and the dent is on the one side and is 3/4", and no dent on the other side,, you now can go to a tire just a little smaller then 7.5" wide.
I know these are not very good examples but you can get the idea of how to find your max tire measurement.