skoda felicia 2000 diesel

Hi,

This is my first Skoda and it's doing a sterling job, need help on a few questions;

The thermostat isn't opening until 90 degrees, is this normal? there's nothing wrong with the head.

Has anyone removed the CAT for an MOT, if so was there any difference?

I have 4 bald tyres (165 13"'s) I have lots of other VW wheels 13 and 14 inch but they are catching on the front calipers, what would be a good 14" replacement.

Thanks for any help,

Paul.