We would suggest using a site such as blackcircles.com where you can view a range of tyres in your size at various price points. You may also wish to consider choosing a tyre with a lower speed rating - ZR tyres are rated for speeds above 149mph, which is probably not necessary for this vehicle. As an example, the Bridgstone Turanza T005 is A rated for fuel consumption, B rated for wet grip and has a low noise level of 69dB, and should be considerably cheaper than the Michelin Pilot Sport.

Tyres that are worn in the centre of the tread is typically caused by overinflation, so if you are fitting new tyres we would recommend having alignment carried out and checking the tyre pressures against the manufacturer's recommendations.