I went to get our tyres checked today and discovered there are a number of fuel-efficient tyre models. I had heard of fuel-efficient tyres before but when I last read about them they were still relatively new and there was little information available about them.
What I discovered
Fuel efficient tyres can increase fuel efficiency by about 8% and are highly likely to save over the life of the tyre. https://www.energywise.govt.nz/energy-labels/energywise-approved-tyres
I didn’t end up purchasing certified fuel efficient tyres as they were considerably beyond our current budget, but I did have our tyres filled with nitrogen instead of air (apparently tyres deflate at a slower rate with pure nitrogen, so tyres are more likely to remain at optimum pressure if still checked regularly) and I bought Enviro Tabs (which increase your fuel economy and reduce the emissions and carbon particulates in exhaust fumes).