Actually this points out why it might be a good analogy. Car manufacturers stick to standard sizes to ensure the buyers can get tyres easily. You don't find BMW or VW specifying a 16.75" or 15.3"wheel diameter, they stick to the standard sizes available.
The only manufacturers bold enough to break that standard are the outrageously expensive niche makers like Lamborghini, Bugatti and Bentley. The customers for these car don't worry so much about paying highly for exclusivity.