I am using 51399 front and 54199 rear. I find the rear is too soft for the hot weather. the rear tire is wearing faster than the front a lot....be careful.
It could be the sponge insert inside the rubber tire. It does not leave too much space between sponge and rubber. So the tire warms up very quickly and over heat faster....I may try to insert a thinner sponge with Tamiya and see if the overheat issue will be solved or not.
I think there is an update on Pit tire review, as they have released new material, which has good grip and long lasting, not sure if HK is available yet.