185mm wide tires are usually fitted on 5,5" rims. However 5" would still be OK. 4,5" makes the tire a bit unstable in my view but not dangerous. The higher the aspect of the tire (60, 65, 70, 80), the less influence the rim width has. Kees Oudesluijs NL [demime 1.01d removed an attachment of type text/x-vcard which had a name of coudesluijs.vcf]