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My car has factory steel wheels with Pirelli 225/65 ZR15 99W tyres.
Need to replace soon with MOT coming up. But at £307 each from Longstone am looking at alternatives.
I assume other members have been faced with this problem.
Do I fit 225/60 tyres which are readily available or change to 16in alloys and fit 225/60 tyres.
What have other members done please. Thanks Roger

You could consider:
215/70 15 +1.26% radius
215/65 15 -1.93% radius (my car has these on 15 inch lattice alloys and they look ok)
which gives you more choice especially at the budget end with decent brands like Nankang to be had for under £50. There are plenty of tyre size calculators online if you want to experiment with other sizes.

Thanks for that Chris - this is something new to me .

By the way in answer to part of your original question, 225/60 15 is not ideal as at -3.56% are a bit on the small size rolling radius wise.

Also note that some alternative sizes are popular van sizes so avoid van tyres if shopping online (although they generally rule themselves out on speed rating).