Pre-selecting tyres in bulk at the start of the year means fleets have to purchase additional tyres for new vehicles when they arrive, bumping up costs.
David Goodyear, AA Tyre Fit's general manager, said: 'Large fleets continue to pay too much for their tyres. It remains widespread for fleet buyers to use their retrospective tyre list to get the best prices on what they believe to be their most popular sizes.
'However, many of these sizes fall out of favour as the composition of the fleet alters, with usually at least a third of vehicles changing every 12 months. Fleet managers must then buy sizes that are not on the list, often at much higher prices.'
Fleets can combat the problem by keeping track of the tyre sizes of new models likely to be launched over the next year, said Goodyear. He added: 'Looking ahead 12 months, we are likely to see the Peugeot 407 and new Volkswagen Golf making an impact in fleet.'