Not perhaps the best location for the spare wheel! But who changes a tire on a turnout run, unless there are no other units which can attend? Speaking of tyres, there was quite a longish period when French fire services all had whitewall tires on their trucks, as they were thought to make them more visibly different from other red painted commercial vehicles. Because tyre manufacturers did not by and large make truck size whitewalls, they were often locally painted and - as can be seen here - sometimes had a quite home made look!
Added by Rob Johnson on 28 May 2022.