Tire Size Question
 

My 7 year old son has a Mirraco Icon with the stock 20x2.125 tires, Alex C303 rims. He's going to try his first triathlon in about a month, and I'm looking for some faster street tires to put on for the triathlon (just a 2 mile bike ride). Would 20x1.5 (40-406) tires fit on his rims? Like these:
http://www.biketiresdirect.com/pkekw...a_kwest/pp.htm

Or do you have any better suggestions?
Thanks!

i beleve those rims are 20x1.75.. so 20x1.75 is the smallest tire you can put on there

I checked and it says on the rims 406x20. Does that indicate the width of the rims? They are X-Rims by Alex, C303.

406x20?? iv never herd of that
measure the width ot the rim and thats your size
1 1/2in = 1.5
1 3/4in=1.75
exct
if the rim will fit those tires it will measure 1 1/2in or less

They will work. 406 is the ISO diameter of the rim and 1.5, 1.75, 2.125 and so on are all 406's. Just watch you don't buy 1-1/2" even though 1.5 equals 1-1/2. When it comes to tires, fractions and decimals don't mix. Our race bikes use 1-1/4" and 1-3/8" tires. They are totally different.