Getting 8 miles less a bar after fitting new tyres!

[Austin-182]

the title might read strange i know....

I have just had 2 new front tyres put on the 1.2 mk2 and we have gone from getting 50-52 miles (per bar on the digital style dials) to now getting 44 miles.

We have gone from hankook k115 to Continental premium contact 5. They are both C rating for petrol and the Continentals are A rating for wet roads compared to the hankooks which are B rating. I only went for the Continentals as they had a better rating in the wet. They also look rubbish compared to the Hankooks. They look like a doughnut where the Hankooks looked like they had more structure to them.

Massively dissapointed as they were £70 each. Size are 185 55 15. Has anyone ever experienced the same? It doesnt make sense that they have the same fuel rating yet we are now getting less miles!

 

[LeeRS]

What does less a bar mean? I cant work it out lol.

 

[Austin-182]

What does less a bar mean? I cant work it out lol.

Lol. The fuel gauge is digital and has around 8 bars when filled up completely. It normally drops down one bar after 50-52 miles. But now its dropping down after just 44 miles.

 

[LeeRS]

Ah. That makes sense now lol.
A lot of factors to take into account though with things like that. Granted 8 miles is quite a variation though.
Im guessing your basing it on driving the same as you always do.

 

[Austin-182]

Ah. That makes sense now lol.
A lot of factors to take into account though with things like that. Granted 8 miles is quite a variation though.
Im guessing your basing it on driving the same as you always do.

No change at all. Everything the same. As soon as the new tyres went on, the miles changed. Wish i had got the Hankooks again

 

[jamesycc]

probably down to a grippier compound as its a better wet rating. Could also be down to the size as they all vary slightly despite the size being the same. Used to sell bicycle tyres and they were never the same between manufacturers despite the stated size being the same. I'm not sure how it works out your fuel mpg but I'm assuming it calculates off a rotating wheel and how far its travelled combined with a fuel tank sensor. If that's the case a slight reduction in tyre diameter means the wheel is rotating slightly more than before and giving you a different reading. The only way to know for sure is to record how many litres/gallons go in and note the mileage on the clock and calculate I yourself. Could be its just as economical but the computer is giving you an erroneous figure.

 

[JB21]

Will be because of different rolling resistance on the new tyre and the weather has gone colder this week so MPG drops there as well.

 

[Budgie]

How the f**k do you notice 8 miles?!

 

[aucky]

if you travelled the same distance with small tyres vs big tyres, the car would think you travelled further on small tyres because there would be more rotations, even if the true distance is the same.
Maybe ~6mm extra radius = 8miles/bar

Just a thought.

 

[Karlos182]

Have you checked your tyre pressures are correct?