Dear all

i am knew to the forum as I am just buying my first lambo gallardo ( to be delivered in June 2008 ).
Is there any problem upgrading the rear tyres of the gallardo spider 2008 from 295/30/19 Y Pirelli PZero on 11x19 rims ( original equipment) to the 305/30/19 Y Pirelli PZero on the same rims.
The difference in diameter,circumference is only 0.9%, well below the maximum 2.5% maximum recommended change.
However, the official dealership refuses to do it?
Any problems anticipated with factory warranty?
Any problems anticipated with handling, traccion control,ESP....?
Thanks
Jondoc