KENDA 24"x2.1" NPJ size concern regarding IUF standard size (618mm)

For competition in the 24" standard class, I’m using a Nimbus 24 with a Kenda NPJ 24"x2.1" tyre

At last November French championship, it was measured within the limits but recently I measured it again to compare with my daughter’s 24" with a Halo Twin Rail 2.2" and now my Nimbus is significantly over the limit, around 624mm :thinking:

Did you ever face such size increase with a Kenda NPJ 24"x2.1" at the same pressure around 4 bars (max pressure written on the tyre is 4.5 bar) ?

I’ve never used the Kenda NPJ but it is not uncommon for tire casings to stretch and grow with time and use (or even just sitting at high pressure).