Tire choice, 145/80R14 or 175/65R15
 

I need to buy new tires soon and IÂ’m wondering which is the right choice.

My original size is 185/60R15.

IÂ’m thinking of these sizes to replace them:
175/65R15
145/80R14

The 175/65R15 are available as fuel efficiency class A tires (Continental ecocontact 6). They are 1% larger than original.
The 145/80R14 are original Lupo 3L tires which have a C fuel efficiency rating (Bridgestone Ecopia B381). They are 2.5% smaller than original.

Go with the 15 inch wheels.
14 is becoming a dead size to some tire manufacturers.
There is a big difference between a fuel economy A and fuel economy C. I put a pair of fuel economy C tires on my nissan leaf it really killed the range. I would have really been in trouble if I had replaced all 4.
And you don't want to go smaller on the diameter.

A narrower tire will have less angular momentum and will decrease energy lost in stop and go traffic. It will also improve aerodynamics. However, an 80 aspect ratio is really tall, and suspension will be better tuned for the 175 width. The tread compound will probably hurt more than the rest helps. I doubt rolling resistance will be lower. I'd also vote for the 175's.

I would just throw on 165/65r14 RE92s in that application but I bet they don’t have them over there

The 175/65-15 is going to give you taller gearing than the 145/80-14. I went with tires that gave taller gearing on an '88 Ford Escort I used to drive and saw an increase in fuel mileage, but the tires I was using were 6.5% larger. Here's another vote for 175/65-14.

I also vote for the 175s, diameter usually helps mileage, and the better compound will help by itself... I went 5.3% taller on my Saturn and gained mileage even though I also went wider

The 175s have a much better rolling resistance rating. You'd have to pump up the 145 width tires to some pretty hefty PSI to match the 175s.

In most cases,
LRR > width

The difference if FE isn't going to pay for a new set of wheels, or eat it all up, so no benefit ...

Far more expensive tyres might not recoup their investment in reduced fuel (depends on fuel price and FE of course).

The 175s are generally a bit cheaper (at least in Belgium) than the 185s.
But difference is minimal.
You can get the Nokian eLine2 in 185/60 ... AA rated and not excessively expensive

The 145/80s are C rated rather than A, and choice is very limited ...


14" is still doing fairly OK in Europe

Smaller diameter rims are generally lighter
Metal is lighter than rubber, so diameter increases are best done using rubber rather than metal ...

I saw a post on the nissan leaf forum where a guy got some ultra light weight racing wheels for his leaf.
New they were over $600 each, he got them second hand for cheap. These wheels where half the weight or about 10 pounds lighter than the stock wheels.
Only increased range by 2%.
You get more range than that just by going with a good LRR tire.

Has anything beat the 165/65/14 re92?