How highly do you rate the Kumhos Nick? They were fitted as OEM to my wife's car but that's a bit different to the Croma.
Interesting question.
When I had the back tyres fitted they seemed no worse for noise and handling compared to the original bridgestones. (bearing in mind the front / rear mix).
I did have an interesting puncture that I drove on and wrecked a new tyre with only 100 miles on it. I had a slow crawl from my house for 2 miles to the motorway at speeds of 20 mph max. When I started off from cold in the morning I could hear a squeeking noise from the rear which I put down to standing overnight and weather change. The squeek soon went away but some 6th sense told me something might not be right. As soon as I got up to about 45 mph on the motorway I know something was wrong. I inflated the tyre with an electric pump and went back to the tyre shop. Outside of the tye looked ok but once it was off ground rubber fell out. Large screw through centre of tyre belt. Grrrrrrr
Where is this going......I think the higher sidewall rating of the Kumhos help masked the puncture at slow speeds. Given exactly the same again but with the Bridgestone I don't know whether I would have been able to spot a flat on those either.
With Kumhos on the front now the noise and handling are again no worse than the Bridgestone. Overall I think the Kumhos will out handle the Bridgestones. I do occasionally drop into race/rally mode in both the wet and the dry and neither tyres have let me down. Point to note is that the 'K's are directional tyres so cross wheel swopping, except in an emergency is not possible.
I do have a possible, very very slight balance issue with the "K's on the front.
This last weekend we drove from Soton to Gatwick. Krys my better half drove first there and she was the first person to take the car over 60mph on the new tyres. Most of the run was cross country so speeds of 70mph+ were rare and certainly very few steadt stright line sections at speed.
I drove one the way back, Mway and dual carrage stuff, and on those times I got above 70mph (say 75 to 85 mph) I could detect a very slight vibration on the steering wheel. I had the tyres checked and one did need to be rebalance but not by much.
Since this rebalance I think I can just, on occasions, detect a very very slight tremor in the steering wheel but not always. Seems to vary with turn radious, carriage way camber, drive power and only at 81 or 82 mph. Also you have to almost will the sensation and be paranoid at the same time
This is such a narrow window I'm tending to think that it is just the way the tread rolls/cuts the road and a natural steering/suspension resonance.
I've decided to run some more miles on the tyres to let them bed, and if I still think I can detect something then get them checked and balanced at another tyre place.
Finally, the "K"s are repspectable budget/cheaper tyres by some 40+ percent. Also the "B"s on the front lasted 24K miles including towing a caravan for 6K miles. I rate this as exceptional performace. The Croma rear geometry problem is what killed the original "B"s in 12K miles and at that time nobody knew if the wear problem could be sorted. That is why I went with the "K"s as an experiment. I certainly wasn't expecting to get to 12K miles with next to zero tyre wear even after my full retrack. Having been more than happy with the "K" rear I took the gamble of "K"s on the front.
I'm up for my second 24K mile service this week. I've asked the garage to check for driveshaft/CV joint wear as when fully warm and driven for say an hour I think there is a little excess play/backlash. It could be that there is driveshaft vibration coming up though the steeering wheel which sort of tallies with steering anlge/camber and drive when this very very slight vibration occurs.
Hope that answers your question.
Nick /////