Hi Stu - I commend you for being brave enough to take on and set up a franchise opportunity. To many it's a great way of running their own business with the backing of a well known brand, etc. Tyre fitting to me looks simple if physical work and am sure having been int he tyre shop a few times could learn the machines in a few hours.
So would I use a mobile fitter - well frankly 'no' I can buy tyres I want on the internet and have them fitted at £40 per wheel inc valve, balancing, etc. and a mobile unit is always perhaps a bit less well equiped than a good shop. However there are many in the corporate world that as Herminator says would. Avoids time off, waiting, etc. To 90% of the population tyres are black things on the corners that are replaced when needed with OEM, the cheapest or what the fitter suggests.
That said the buddy of mine that runs the village shop also runs a huge fleet of mobile vans and fits most of the premium tyres in the NE of Birmingham area.
To me the success of this would be to identify who will be your customers, what is your competitive advantage in the area, how will you attract them, etc. Can you fit enough tyres in a month and every month to pay franchise costs, fuel and make a decent living?? Why not spend a day with an existing franchisee and see whathe does?