How old are they ? Check the manufacturing date code !
I made the mistake of running the KR1 with "what it came with" - the front Pirelli looked as though it had done minimal mileage & the rear Bridgestone was less than half done. It passed the MoT fine, but the front let go on a roundabout at little over walking pace on the way back from the test.
If I had been going a bit faster I might have slid - as it was I sort of tumbled & broke my collar bone with a "classic helmet rim" incident as my collar bone took my full weight on the edge of the helmet.
Turned out the "new" Pirelli was over 7 years old & had gone hard - add in a well worn road surface on the roundabout (outside an industrial estate) & I was off before I knew what was happening. The following car driver who offered assistance seemed more shocked than I was. The remainder of the ride home was "interesting" - the bike only suffered a broken rear brake lever & mirror. Mrs B said I actually looked green - her first words were "You've come off, havn't you" before I said anything.
4 weeks off work & the collar bone didn't set in the right place (local hospital couldn't be bothered to check it was setting where it should be - "they sort themselves out - go home & rest" ) so my right shoulder is now lower than the left.
A new pair of tyres from the off would have been a lot less painful to both self & bank account - particularly as I had intended to fit them anyway.
If in doubt - swap 'em out ! You know it makes sense.