Wheels choice
 

Hello all,

I am about to change my wheels.
I have two options :

Stick with the 195 65 R15 wheels where I intend to have the least RR tire available (namely Bridgestone Ecopia EP001s) on the rear only (the front have some thread left)

Retrofit the 205 50 R17 wheels I had previously but with 205 55 R17 for a significant (?) 4.8% increase in perimeter.

My mileage is 25% highway (from 70 to 83 mph), 37.5% errands (around 50mph) 37.5% city but it is about to change towards much less city.

Regarding potential in FE increase, I am not after a short term return on investment, I consider the chase for the MPG number and least impact on environement rewarding already (within reason !)

So, what is your opinion ?

Alternatively, what difference in RR should I put in the calculator to evaluate the impact ?

tIf you want to increase the diameter, it's better to do it with higher sidewalls rather than wider tires and larger rims.

You could go with small truck tires like 195/75 R16, they don't have the best class but still a very good B class. It's 10.2% bigger, though. Did you measure how much room you had left for bigger tires? On the AX, the limit was about 10% bigger.

To know how much rpm loss will affect efficiency, you can compare max rpm and and rpm at max speed in final gear.

Something I forgot to say :
205 60 R17 is the tire size of the Scenic (technical sister of the Megane estate) so technically I could have my speedo properly calibrated and blame my ignorance in the event of a police control.

Also, speed index is mandatory and subject to a fine much more easily than a wrong tire size of a sister model of the same brand ...

weight difference between the 17's i took off and the stock 15's i put on were at least 10# each but i will have to dig up the exact info. T rated tires are a hard compound.
i run Cooper CS4 195/65/15-91T, rated for 80,000 miles. mileage jumped into the 50's after that.

Those are A A rated, aren't they ?

Nokian seem to have pulled the plug on their eLine A rated tyre ... they're no longer on their website ?

I wouldn't go wider if you're after top FE, nor would I get bigger wheels - unless you're willing to invest serious money in very light rims.

Eco tyre availability in 205/55/17 is even worse than in 205/50/17 (which are very expensive).

You'd end up with a heavier wheel+tyre combination, and couldn't get the best rolling tyres for it.
You'd be losing FE @ both ends.

I'd stick with the 15" and get the best rated tyres for them.
If possible with a higher LI than what you actually need so the sidewalls are stiffer.

Yes, they are the one, both better on FE than the Michelin and less noisy @ 69dB rather than 71dB.

Can't seem to find Nokian tires in France nor it is a brand I have heard of before


95 rated tires for load index are not as good rated FE wise than 91 rated tires.
Also they are "reinfoced" so I expect them to be heavier.

Here is a really important test for you to consider (if you have not already seen it). It is in the middle of the thread, but it was probably the best single test done on this topic on this site (I think all would agree):
http://ecomodder.com/forum/showthrea...tml#post246084

Good luck,
james

In the end I went for the Bridgestone ECOPIA EP001S in standard smallest homologated for my car wheels, namely 195 65 R15.

The fitting company had my car by 14:00, promised it back for 16:00, at 16:21, I went to the counter to ask if the car was OK, it was not and I knew it so they promised it within 15 minutes and I got it back at 16:51 !

That's almost one hour late over their really comfortable 2 hours allocated time.
I wouldn't recommend them if the tires weren't 10 euros cheaper than elsewhere ...

Some time this week I'll showyou a pic of the tires, they are very shallow in the marking department (no stated side wall max for instance), that may bee part of their low noise / high efficiency ranking ...