Which spare wheel and tyre size should I buy for my Nissan X-Trail?

I have a 2011 Nissan X-Trail Tekna 2.0DCI 173 manual that I bought for towing a caravan. I realise now that they do not supply a full size spare wheel, and the 'get you home' wheel stipulates in the owners handbook that you cannot tow with this type of wheel. The local dealer has quoted a figure of £800 for a full size spare wheel. The owners handbook lists three sizes of tyres: 215/65R16, 225/60R17 and 225/55R18, which is the size fitted to my vehicle. What are the disadvantage/advantages of the 225/55R18 over the other two sizes, and could the other sizes of tyres fit my vehicle with the appropriate wheel rims (which are:- 16 x 6.5J, offset 45mm (steel and aluminium); 17 x 7J, offset 40mm (aluminium); and 18 x 7J, offset 40mm (aluminium).

Asked on 26 January 2013 by KN, St Austell, Cornwall

Answered by Honest John
All these wheel and tyre combinations will have approximately the same rolling circumference, but any slight difference will interfere with and damage the car's 4WD system. So, if buying just one wheel and tyre, you need an exact match. But it's better to search around for a salvaged one than pay £800: www.honestjohn.co.uk/useful-websites/parts-accesso.../
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