My Volvo XC70 AWD (current model) is fitted with Pirelli Scorpion Zero 235/55 17 99V tyres all round. The rear pair are worn down to 2mm and need replacing. Is there any reason why I should not fit tyres with an H rating such as the Pirelli Scorpion STR or the Bridgestone EL42, provided they are fitted as a pair on the same axle? The saving would be substantial. We never have occasion to get anywhere near the 'H' speed limit of 130mph and off-roading is usually just a matter of hauling a horse trailer across grass fields and farm tracks.