About a month ago I put on 195/50R15s to replace my std 185/55/R15s.
I dont know if its the tyres or the suspension - I have checked the rear suspension and it seems firm enough but it does creek!
Anyway to the point - I took the Williams along Loch Ness Side on the old tyres - at the end of the run coming into Inverness there is a left into a right then a sharpish downhill into a long (bumpy) straight. I flew though this and hit 110mph on the straight before slowing off to 30 as I came into Inverness.
I tried this route tonight and as the tyres have less give it was a bit more bumpy BUT on the left into right the car felt very unsettled and the rear felt like it was moving (heart stopped). Then on the straight about 85-90mph was as much as felt safe - I tried 100mph as I had done it before but the car was very unsettled and almost dangerous.
I had a similar experience when late for work - on the dual carrageway - it felt quite unsettled at high speed (90-100) where as my old Fiesta RS had travelled the same but of road at 30-40mph more with more confidence.
Now this could be down to the tyres - or is there something ion my suspension I should be looking at? Sorry for the long post and no I dont drive everywhere at 100mph