Pirelli P Zero tyres

[RogerB]

Towcar is Audi A4 cabrio 3.0Tdi S line Quattro Auto and van is Olympus 534.Towing ratio is around 83%
Recently changed all 4 tyres to Pirelli PZero Rosso from Continentals.The steering now feels less precise than before driving solo and the van feels a bit twitchy and nervous when towing.Has anybody else noticed anything similar?
The van is loaded correctly and I have just managed to acieve 80kg noseweight but having nothing but 1 light bottle in the front locker.There is NOTHING else forward of the axle.All heavy items on the floor over the axle and medium weights under the bed.By loading like this I can just achieve 80kg nose.
The changing of the tyres coincided with the arrival of the new van so I'm not sure if the tyres are causing the nervous towing or if it is the loading.My old Senator was loaded the same way and towed like a dream but the Continentals were on the car then.
Any thoughts please.

 

[Icemaker]

We had these tyres fitted to our 2.0 tdi alhambra after i had the car re-mapped to 170 bhp thinking they would be far more suitable to the power we now had, unfortunately we suffered jittery ride and poor wet weather grip but by far the worst problem was the life span of the tyres, just 5000 miles from the front set and 9000 from the rears which is ridiculous for tyres costing over £100 each.
i had toyo tyres fitted after this and sold the car with these still fitted after just over 10.000 miles and they still had a few thousand left in them.
we now have a transit 2.2 tdci 140 since we have purchased a house to renovate in france and need the load ability for the materials, the van came with michelin tyres fitted and the front ones are completely shot already at just 10.000 miles, seems to me that the brands we have been told are the best may not be !!.