@Martin_z_BA Get thee a torque wrench and ATV jack and prosper. It will take you less time, even the first time, than the time to ride to the shop and wait, or drop off and return later (tying up someone else to transport you). The manual is in Resources at the top of this page and there are many of us here to help- if needed.
As far as Avons vs. Cruisetecs - I like the later (a lot), but since they don't feel like making them enough to keep in stock, I won't give them my business anymore. I called Metzler and got a real "could give a $hite" attitude when asked when they were going to produce more. "Ask your dealer," he said in response to everything I said, as if a retailer would know more than Metzler itself.
The solution (and improvement) is the Exedra Max on the rear and a number of choices for the front (there is a current thread on this), my latest being the Dunlop Elite. The taller Max on the rear will shorten the rake of the bike giving better handling in the twisties. There is nothing magical about sticking with one of Triumph's recommended tires of the year. They switch oil brands too- it's a business relationship with them, not a requirement for us.