Most Darlington fittings take around 20-30 minutes per tyre with the vehicle in the bay. Two tyres would take around 45-60 minutes. More time would be needed for balancing or adjustments for valves and alignment.
Next day appointments in Darlington are likely, as long as there is stock of the tyres, and if the garages are open. Once you provide your registration or the size of your tyre you can see the earliest time slots.
For some postcodes, mobile fitters in Darlington can be booked as well. The fastest way to check this is by conducting a booking search and selecting the mobile option, and/or booking a garage in Darlington.
The fastest way to get matched Darlington tyres is to provide your registration, but you can also search for tyres by size. The size is usually on the sidewall of the tyre. You can find it in your handbook as well. Check the existing fitment load and speed rating.