Tyre Choice And Fuel Economy

[munch]

Its my first time replacing tyres on my IS200 so I changed my old Bridgestone Potenza RE 050 A 215/45R17 to Goodyear Eagle F1 GSD3 215/45R17 and have noticed a dramatic reduction in fuel economy.

I am driving a 05 automatic IS200 (my second) which i have had since february. Almost like clockwork the fuel gauge used to hit each of the large markers every 150km and the low fuel light would come on at 568-695km. Since i have changed tyres i am getting significantly reduced economy. Hitting the large markers at 135ish and getting 490 to 515km when the low fuel light comes on.

The tyre pressure is perfect, i have even turned off the air conditioning to try to get better fuel economy but with little effect and i am travelling the same route 90% of the time. The bridgestones were a bit worn but still have a few thousand miles left on them, in fact it feels like i have less grip on the F1's and they tend to tramline much more easily than the bridgestones.

I know that the prius has crappy tyres that help give better fuel economy but can it make that much of a difference with two similarly specced tyres? It may help explain the confusion surrounding differing fuel economy that i have read in many threads on this site.

Any insight into this would be welcome.

[ColinBarber]

Goodyear F1s are ultra performance tyres. They have excellent grip and together with the tread pattern do not provide excellent fuel economy. Performance and economy just do not go together.

However you state the F1 feel like they have less grip and tramline so I would strongly recommend you get a full 4 wheel geometry check.

[munch]

She is due for a service in a couple of weeks and alignment is top of the list. but i have a few questions.

I do a lot of B road driving which is probably making a bigger difference as opposed to motorway driving. Do you not think that loosing 10-15% of fuel economy is excessive?

In the countless MPG comparison threads here i've never seen anyone mentioning that tyres can make a massive difference to fuel economy. Is it because it is so blindingly obvious that i should have factored that in or is it something that people don't know or like to talk about?

Finally. For the careful motorist what would be considered a decent tyre which would give good grip and excellent fuel economy.

Thanks,

Rob

[Mike_B]

Never occurred to me that the F1s would make a difference to fuel economy, at least not by that much. I run them and have to say that I think they tramline a lot *less* than the Bridgstone RE040s that were on before. But then it might simply be that the old ones were very worn, whereas the new ones were obviously not. The ride was noticeably better with the new ones too.

But it's interesting you note the sharply worse economy. I have noticed that it's not as good on a run as it used to be - maybe that's why!

[Paradroid]

When did you change your tyres? My IS200 economy has dropped with the weather being cold. In summer I'd get 210-220 miles from 1/2 a tank, now it's more like 180.

Just wondering if it's a coincidence.

The other possibility is to play around with the pressures. I have Vredestein tyres on my car, and their web site recommends 41psi for their Ultrac tyres on the IS200 (they have specific values for lots of makes of car). At first I thought they were insane and kept it at 35psi. But steadily I increased the pressures and 41psi definitely feels right, the handling and stability is spot on and wear is completely even.

I'm not saying everyone should go and put 41psi in their tyres right now, different makes will need different pressures.

But in your case you've got tramlining and bad fuel economy so it could be underinflation. What pressures do you have in now?

[munch]

i changed them in november just after that cold spell we had so i've experienced both tyres in cold conditions and recently we had a warmish spell and still the MPG suffered. I have turned off my air conditioning for the last month because of the low fuel economy and it made little difference.

I will go and check the tyre pressure at lunchtime and give you an exact readout.

[munch]

all tyres were in the region of 31-33 PSI so I bumped them up to 37-38. Will that make much of a difference?

[dave1]

all tyres were in the region of 31-33 PSI so I bumped them up to 37-38. Will that make much of a difference?

What made you increase your tyre pressure to 37-38 psi ? What pressure do the tyre manufacturer suggest for your car ? Fuel consumption will always be lower in cold weather. Various things will affect mpg. Are your brakes running free with no binding due to weather? You say due for service so I would expect that to be the main reason coupled with drop in temperature. Put your tyres to recommended pressure, get car serviced and then see what transpires.

[ColinBarber]

depending on the load in the vehicle and your average speeds 38 is normally too high. You will wear the middle of the tyres, will have less grip and a hard ride.

[munch]

all tyres were in the region of 31-33 PSI so I bumped them up to 37-38. Will that make much of a difference?

What made you increase your tyre pressure to 37-38 psi ? What pressure do the tyre manufacturer suggest for your car ? Fuel consumption will always be lower in cold weather. Various things will affect mpg. Are your brakes running free with no binding due to weather? You say due for service so I would expect that to be the main reason coupled with drop in temperature. Put your tyres to recommended pressure, get car serviced and then see what transpires.

The economy dropped the instant the wheels were changed. In fact i filled up the tank after about 30km and noticed that at the first large marker on the fuel gauge i was down in fuel economy by 15km with only 135km travelled. That must rule out the weather/brakes/service unless the guys changing the tyres did a botched job.

[ColinBarber]

worth jacking up each wheel and making sure it spins freely to rule out brake binding.

Are the tyres rotating in the correct direction?

[munch]

worth jacking up each wheel and making sure it spins freely to rule out brake binding.

Are the tyres rotating in the correct direction?

The direction of the wheel was the first thing i checked when i noticed a loss of grip which was initially down to brand new tyres.

i'll send the car in for aligment later this week and let you know if they find anything suspect.

[Paradroid]

depending on the load in the vehicle and your average speeds 38 is normally too high. You will wear the middle of the tyres, will have less grip and a hard ride.

It depends on the tyres. As I said above 41psi is the recommended level for my tyres on the IS200. They are wearing perfectly even.

I think it's generally agreed that 35psi is more sensible a starting point than the 32psi the manufacturer recommends. That's WIM's recommendation I think.

[munch]

Sorry for the delay in getting back. I'm sure you are all waiting with baited breath.

Alignment threw up no surprises, also the service, air filter, new plugs etc. No change in economy.

The most important thing is the lexus mechanic who looked at my car used to work in BMW in dublin and he said that on a number of occasions people would bring back GOODYEAR EAGLE F1's because of the massive drop in fuel economy.

Goodyear Eagle F1's can cause your car to loose 10-15% fuel economy. That is a lot.

[reddevil]

when i had my mini i had avon zv3 s and falken fk452 s on all 4 wheels (at different times abviously) and found that the avons' were brilliant tyres but did use about 20% more fuel! this was in as close to a control environment as you could reasonably get on the road as tyres were changed at almost the same time 2 years in a row, coupled with servicing. i drove the same route to work at the same times every day and in all weather conditions!