Typical tyre fitting at local garages takes between half an hour and one hour. It depends on how busy they are, how many tyres you need fitted, and whether or not you have any additional requests like wheel alignment or any problems like a stuck locking wheel nut.
In Dorchester, next day fitting is usually available, but it will depend on the inventory of the tyres you have requested as well as the current bookings at the affiliated garages. Please check the booking calendar after you've searched for the earliest availability for your chosen tyres.
From where you are, mobile tyre fitting may be available in and around Dorchester. After you search for and select your tyres, you'll see if mobile tyre fitting is an option or if you'll need to book a fitting at a garage.
In the case of tyres suitable for Dorset's seasonal changes, the best option is use of all-season tyres as they cope quite well with wet conditions in addition to performing better with the lower temperatures when compared to summer tyres. For the drivers of rural roads in the winter with the added predicament of driving during the early hours of the morning, winter tyres would be best. Drivers who prioritise speedy performance in the summer would prefer the use of summer tyres.