what TYPE of tire is the most fuel efficient?

[Blue07CivicEX]

Originally Posted by an0nymous

I'm a newbie and this my first post. Just bought a 1998 metro and got to looking around on the internet...
So apologies in advance for the stupidity:
Anybody ever run the 4 doughnut spares.. rated 60 psi, narrow profile... seems like that could be a winner?

One issue I would worry about with those is stopping, swerving quickly or on wet roads. I think they would be fantastic for FE but might not be great for the nut behind the wheel (safety)

[rmay635703]

Thats exactly what I run on my Comutacar, but mainly for size reasons.

As to Blue07Civic they are not that bad on traction assuming you are on blacktop and not on extremely rough roads. Not much different than summer treads with 50% left.

To anonymous If you do run donuts remember like racing slicks

a. You will not have as good of traction in light water and during the initial spotting of rain, deep water you will have better traction because its downright impossible to hydroplain, you don't have good dirt traction, you have better glare ice traction, good snow traction assuming you have enough weight to cut through the snow but if not it won't be good at all, much like running worn summer treads. Slush is a NO NO period.

b. You must measure the outer dimensions of your tires that are supposed to be on the car and try to find donuts that have similar dimensions with the same lug pattern, it may not be doable, if not you will need to calculate your REAL speed and real mileage or it will end up being moot and meaningless and your speed will not be known.

c. Weight - contrary to popular belief donuts can last a long time and run faster than 50MPH IFF your car is significantly lighter than the intended vehicle. Donuts are actually stronger built than standard tires and have a nearly unpoppable inner nylon skin (I know from experience 3 of my donuts are 12 years old with god knows how many miles plus my 3.2k from last year)

d. Handling - you MUST drive paying VERY close attention to HOW BUMPY the road is with donuts or you will BE VERY DANGEROUS!!! Donuts under most circumstances handle very well and have just as good of traction as normal tires, they obviously work best on new smooth roads, if your roads aren't smooth you damn well better slow down or swerve if you see VERY LARGE bumps and you better not be driving too fast if your roads are terrible AKA you will be stuck to city speeds. If you are a good driver you may be able to compensate somewhat but until you put them on your vehicle and get a taste you won't know how good your suspenion etc will work with them, lightweight is better but you can literally get lanched on railroad tracks and other large bumpy obstacles if you aren't carefull when you have them. Potholes should be avoided, vibrating roads (very deep quickly repeated cracks) with a poor suspension can litterally move you off the side of the road at high speeds.

Hopefully this explains a little, I honestly am not scared of using them because I know the area well and regardless of situation the brakes always work.

As a note HARD rubber tires give you the best milage (over inflateables) but you couldn't travel much over 35mph on most roads, there may be applications for these type of tires assumeing the driver would use them in the situations they would operate safely under (a better suspension technology would assist in safety but our suspensions aren't configured for these tires)

Good Luck

Originally Posted by an0nymous

I'm a newbie and this my first post. Just bought a 1998 metro and got to looking around on the internet...
So apologies in advance for the stupidity:
Anybody ever run the 4 doughnut spares.. rated 60 psi, narrow profile... seems like that could be a winner?

[brucepick]

Yes I agree with what's already been posted:
Circumferential grooves will be better than crosswise grooves.
'Performance' tires will likely have higher rolling resistance to get better traction.

Also pay attention to the tire's weight (you can see weight in TireRack specs). Rotating weight is supposedly 3x as harmful to your mpg as non-rotating weight, which is why people bother looking for lightweight alloy rims.

BUT here's what I did when I bought tires nearly a year ago:
I made sure I got tires rated for 44 psi, and not 32 or 35 psi.
If I'd had the money available I might have gotten tires rated at 52 psi.

I dared to run my old 35 psi tires around 40. I run the new 44 psi tires around 52. I don't think I'd want to run 35 psi tires that high. The increased pressure really helps fuel economy.

A few years ago there were some efforts to get specs published for all new tires, showing their rolling resistance. Big business (that's Big Oil) and government got together, and made sure that legislation got killed off. If you're reading this in the USA, be sure to vote this November!

[chrislk1986]

Originally Posted by Blue07CivicEX

One issue I would worry about with those is stopping, swerving quickly or on wet roads. I think they would be fantastic for FE but might not be great for the nut behind the wheel (safety)

It'll throw off your speedometer. So unless you calibrate it, it'll most likely show a good increase in FE when you might be getting the same or just slightly better mpg.

And I think the tread life on those are low. I don't have one here to look at but the last time I saw a spare, it looked like it might last 4 months max.

I'll add that for city driving it would probably work excellent and might last all year.