Tyres mpg

Forum for wheels, tyres, suspension, chassis, brakes
Donkey
Posts: 1791
Joined: Sat Mar 15, 2014 2:43 pm

Post by Donkey »

I wonder if its the tyres saving fuel or the wheel sizeAgrea with MJCQC re rolling resistance and weight The AP I had was more economical following a Tekna to bottom of Spain in convey by about 8 euros a tiny amount but then we cant say both cars were same weight

F1 Bob
Posts: 546
Joined: Sat Mar 22, 2014 12:26 pm

Post by F1 Bob »

Some interesting views here and thanks Guys. The Continental tyres had only done 6k when removed and there was no appreciable wear on them. As stated above the overal diameter of the wheel and tyre remains unchanged (almost).The original setup was 225/45 R19 and this has changed to 215/60 R17. As such the rims reduced from 19" to 17"The tyre depth increased from 3.99 to 5.08"Overal diameter increased from 26.97" to 27.16"When the speedo reads 30 mph the actual speed will be 30.21 mph. (Give or take for normal under read for cars speedo which is around 3 mph).
Pulsar 1.5 dCi Tekna in Bronze
MJCQQ
Posts: 136
Joined: Sun Oct 12, 2014 8:54 pm

Post by MJCQQ »

Basically it boils down to the fact that if rolling resistance increases, fuel economy decreases.
F1 Bob
Posts: 546
Joined: Sat Mar 22, 2014 12:26 pm

Post by F1 Bob »

Yes, I guess the key here is the reduction from 225 to 215 which must reduce the rolling resistance. Plus the tyre compound might be having some effect as well.
Pulsar 1.5 dCi Tekna in Bronze
MJCQQ
Posts: 136
Joined: Sun Oct 12, 2014 8:54 pm

Post by MJCQQ »

Exactly and combined with the lighter wheel you are noticing a fairly large improvement in fuel economy. So a combination of thinner tyres and lighter wheels = better fuel economy.
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