You can do a tyre change without refuelling but I wouldn't recommend it. To do this you have to over fuel and then be on line to force the cars to pit because they will only auto-pit when triggered by the car having insufficient fuel to do another lap.
The fuel load you specify for the next pit stop is what the pit crew will top your car up to. So for example if you instruct 30 litres:
- Your car pits with 1 litre remaining the pit crew will add 29 litres and change tyres.
- Your car pits with 20 litres remaining the pit crew add 10 litres and change tyres.
- Your car pits with 31 litres remaining the pit crew will only change tyres.
So by putting two stints worth of fuel in the car at the start of the race you can manually force the car to pit for tyres only. The reason I wouldn't recommend it is that a) I don't think the pit stop time is reduced for a "tyre only" stop and b) your cars will have been handicapped by carrying excess fuel weight for an entire stint.
