tire size fuel efficency 165/60/r14 , 165/80/r14, 155/80r14

[somerandomguy]

Good afternoon,

which of these tire sizes provide more fuel efficiency on a 1990 toyota corolla 1.8 diesel sedan.

165/60/r14 and 165/80r14 are wider than 155/80r14 which is not good for fuel efficiency.

the 165/80r14 has a larger circuference and diameter, which is better perhpas for highway driving?

the 165/60/r14 have smaller circunference and diamter, which is better for city driving?

thanks

[CapriRacer]

The difference between tires in different sizes - all other things being equal - is small compared to the differences between make and models (up to 60%)

So you should concentrate on the make and model first, before you tackle the size thing.

But to answer your question, a 165/80R14 is 7% better for RR than a 165/60R14, while is 155/80R14 is only 5% better) - but I doubt you can fit a 165/80R14 under the fenders of a Corolla.

But the above doesn't take into account the affect the rolling diameter will have on engine performance. I don't think you can quantify that to any degree of precision, especially given that we don't know how you use the vehicle. Lots of stop and go driving consumes a lot of fuel compared to the distance traveled, so any improvement a different tire will give you is going to be small compared to the weight being accelerated.

Also, you've posted a similar question at Bob is the Oil Guy.com. You're sort of getting the same answers there.

[rmay635703]

I would guess the Bridgestone Ponteza 165/65r14 would be the best fit overall but you would need to use the European comparison metric for tires intended to fit yourcar

[cRiPpLe_rOoStEr]

155/80 seems to provide a better balance of city and highway performance, as its diameter is halfway between the other sizes, plus its narrower tread is also likely to decrease rolling resistence considering all the sets to use a similar rubber compound.

[oil pan 4]

On road testing shows bigger is better.

[cRiPpLe_rOoStEr]

Originally Posted by oil pan 4

On road testing shows bigger is better.

It depends on the terrain and traffic conditions, not to mention the engine of that Corolla is not a torque monster at all.

[somerandomguy]

Barrys tire tech page says that wider tires provide better fuel efficiecy, if this is so why do vehicles in fuel economy competitions have narrow tall tires?

[CapriRacer]

Originally Posted by somerandomguy

Barrys tire tech page says that wider tires provide better fuel efficiency, if this is so why do vehicles in fuel economy competitions have narrow tall tires?

Because vehicles in FE competitions are designed to be light and aerodynamic, and that means those 2 properties play a larger role that in street cars - and both of those favor tall narrow tires.

Plus, ride comfort is not a consideration in a FE competition, so they inflate the crap out of those tires - and that means they can use even narrower tires.