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I have had several cars, which have all been "sporty", fuel economy has never been a requirement.

Now it is. So I've bought a little 1.2 petrol which gives me 65mpg on the motorway/highway and 40mpg around town.

The car weighs a shade over 800kg and has 165/70/14 tyres on as standard.

I'm wondering if it's safe to fit narrower tyres, and maybe even increase the rolling radius to further improve fuel economy. I understand narrower tyres offer less grip, but during my current need for fuel economy I'm driving well within the limits and being very gentle with the car.

Any thoughts / advice is much appreciated.

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1 Answer 1

Two things: First, you could get skinnier tires on there, but I wouldn't. You won't gain any mileage from doing so. You'll incur the cost of tires, so will cost you more in the process. Second, putting taller tires on there to increase your rolling radius will hamper improved fuel mileage. The reason is because taller tires require more torque to run the vehicle. To provide the additional torque, you'll be harder into the gas pedal and using more fuel to make it happen.

As an aside ... you are already getting 65/40mpg ... and you want to improve on this? I doubt it's going to happen, especially with a 1.2L engine. Just not much room there to get better mileage. There aren't too many vehicles on the road today getting better mileage that what you are experiencing.

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Hi, thanks for the response. I live in the UK, and here petrol costs $2.31 of your dollars per Litre. There are lots of cars here achieving far better than 65/40mpg. Some are getting 80mpg on the motorway and over 65 around town, but they're using better technology than mine, granted, i.e, stop/start, better injection methods, etc. There is some benefits to be had though I'm sure. I used to get 12mpg from my last car, so I'm trying to get all I possibly can from this! :D Your second point is well received, thanks, but can you expand on the first point? Would it be dangerous? –  i-CONICA Jul 7 at 15:42
    
@i-CONICA ... No danger at all. Obviously, you don't have a corner carver, so lateral traction is not in question. You may pick up a couple of 1/10ths of a mile per gallon, but nothing dramatic. Definitely not worth the expense of replacing them. Also, I would bet those other cars you mention are hybrids of some sort, no way to match what they provide in a small go getter car. Your best bet is to ensure you are driving your car as lightly as possible: don't try to got rod it because it isn't one. Long braking, easy take offs. This will be your best bet at the best mileage. –  Paulster2 Jul 7 at 22:58
    
Also note that English gallon is larger than US gallon, that’s why British MPG figures are different from American. –  theUg Jul 8 at 11:58

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