Did a practice day this week with our two Top kart Rotaxes which both have different tires on them. The karts are identical aside from the tires. One has MG’s and the other one has Bridgestones. Both sets are the same age and have about 10 - 20 minute sessions on them. I have always driven the kart with the Bridgestones but this time after the first session my daughter and I switched karts. I knew the MG’s are harder compound than the Bridgestones but I was really surprised at how big of a difference there really is! I spun twice on my first fast lap and was locking up coming into turns with heavy braking.
We are not racing so it doesn’t really make a difference to us just that I will always want the kart with the Bridgestones now until they no longer perform 
I’m not sure exactly what is going on there but your tire code “SKH” for your “MG” tire is actually the tire code that was normally used for for older homologation (2020-2023) Evinco Blues (which is made by MG).
Current generation (2024-2026) Evinco blue tires carry the SKH2 code, and current gen MG’s Red (the same tire as Evinco but with different branding) typically carry the SH2 code, and older (pre-2024) were SH.
I think it’s safe/likely to say that your tire is not current gen in any case, but I’m pretty sure that either way your MG is not the typical MG tire seen here state side. Will be interesting to see if anyone can shed any light on this situation.
An old spec SKH is a pretty hard tire. Not really ideal for Rotax, even when new. But if it has some years of age and sitting they’re going to be even worse. That’s a harder tire than KA runs now.
Very stiff sidewall on those so they like to snap more easily at max load.
This is why people recommend to test on tires you are going to race on. Not relevant to your situation John, but easy to see how big of a difference the tire can make.
Other than delaminating at inopportune times… that YLR was a heck of a good tire. Yeah it’ll be miles better than that era MG.
Coin flip for who gets the good tires! lol
Should be able to score plenty of used tires out there from the big teams. They are dying to part ways with tires after a national.