Alright, so I put my wheels together today and 'dressed' the tyres.
The stock tyres on the Kronos XTR weigh 315g,

vs the belted JetKo Tyres at 441g -
- that's a 28.5% heavier wheel/ tyre combo folks!
But being belted means better stability, predictability, more contact patch and thus more traction on tarmac. Hopefully all these benefits will outweigh the additional rotating mass.
A really neat idea are the removable hexes. Note the castellated shape here with hex still being tightened. 8 x M3 bolts hold the hexes in place and it's definitely worth doing these by hand. In theory you can remove the hex and change to a different size if you swap, say, from a Corally to a Traxass.
It's not easy to tell how tight to take them, as the amount of torque required for the bolts to pass through the wheel feels just the same as it does when it enters into the hexes. Do the tightening order properly, tightening opposing bolts all the way round until it looks like this.

There's absolutely no need to over-do the torque on these, else the threads will strip out in the hexes and your wheels will be parting company from your truck very soon!
The tyres come with nifty, zip lock bags - so easy tiger - no need to cut them like I started to do - they're actually pretty handy to store your stock tyres.
Included are some stickers - one pair of tyres had a set of JetKo Cyotes, which is definitely going on the body.
The other pair had 'top best tyre'

stickers - which I'm sure is quaint English but whatever - I'm preferring the coyotes!

For Kronos and Kraton etc JetKo recommended the 1/2" offset wheels. They clear everything fine, but the truck is definitely wider now by about an inch. This is likely a good thing if you want to try some speed runs on-road.
These road tyres are marginally smaller diameter, so this will lower the roll-out slightly, effectively lowering the gearing.

Fitted, they look absolutely bang on. Unlike some smaller scale trucks, the proportions are just right with these for 1:8th.

These tyres are described as medium soft (green) compound. The rubber is sticky at room temperature and likely be even stickier when running. I have absolutely no doubt that these are going to grip like hell on smooth, hard surfaces.
On dirty, loose or dusty areas, these tyres will just pick it all up like blutac and need to be scrubbed to get the traction back up again - just like full-size tyres.
Obviously, I can't wait to try them out! I'll head down the local showground while it's quiet. I'm sure that I'll break my personal speed record with these fitted.
The overall quality seems excellent. The fit and finish of the wheels, tyres and hexes are without fault.

My Dusty Motors shroud looks just like the latest truggy bodies! Better in fact...
I haven't fitted the sock shocks yet, which came supplied with the shroud, but I'll give them a go. I use them on my Baja 5B SS and they definitely help prolong the life of the seals and shafts etc.
I'm very pleased with the items, all of which arrived the next day from Modelsport via DPD - free postage!
So, shout out to Modelsport. Couldn't have done it quicker or cheaper.