Here's my car...

[LostCause]

Sorry, I meant a 155/85/13.

Even if they don't work, I'd still be interested. I'm just brainstorming a non-roadgoing vehicle at the moment and those tires look perfect.

- LostCause

[trikkonceptz]

If I may interject, VW beetles use to run a 145/15, which was the skinniest tire I ever new until we began lowering beetles and running doughnuts as tires, which I think were 125/15's.

www.whitewallcandystore.com search under beetle and you wil see them there. $160 each I think

Good Luck

[cbergeron]

Those tires are 115/70D14's.

They're very tiny.

[cbergeron]

I've added moon hubcaps, swapped my rear wheels with thinner profile "donuts" and I saw a significant boost in MPGs.

Here's a more recent picture of my car/mods:

[cbergeron]

It should be noted that by having small/thin tires on the back of the car, the steering is very "boatish". By boatish I mean she has a boat-tail effect to her, so at high speeds she's very unstable. It's like pushing a shopping cart in reverse.

I can't drive her beyond 55 mph in this configuration. Since she's my commuter car and I work close to home I don't ever need to drive her any faster, so it works out quite well.

[IndyIan]

Originally Posted by cbergeron

It should be noted that by having small/thin tires on the back of the car, the steering is very "boatish". By boatish I mean she has a boat-tail effect to her, so at high speeds she's very unstable. It's like pushing a shopping cart in reverse.

I can't drive her beyond 55 mph in this configuration. Since she's my commuter car and I work close to home I don't ever need to drive her any faster, so it works out quite well.

Yikes! I'd imagine you could have alot of oversteer with those back tires! I have 155/85R13 snowtires for my neon and even those result in boatish handling although balanced with 4 on. If you are going to run significantly skinnier tires on the back you should do a couple of parking lot tests for steady state cornering and then some hard braking while turning hard, just to see if you have understeer or (hopefully not) wild snap oversteer. I'd bet with skinny 13's your car now has balanced handling and not hopeless understeer like most cars but you should check.
I'd imagine an Aspire could be rolled if its suddenly sideways at 55mph. Mpg tends to drop when sliding on the roof....
Not trying to scare you but you should atleast practice abit with an extreme tire setup so its not a surprise in your first accident avoidence maneuver.
Play safe!
Ian

[Tripleskate]

Woah, those rears are so tiny! It seems like they would effect the overall ride comfort of your car? Any truth to my theory?

[MetroMPG]

IndyIan offers good advice, I'd say. Safety first, etc. etc!

To clarify the mpg boost you saw, are you saying you saw the gain when you went from wider tires all around to 2 narrow fronts plus the rear donuts? Or you saw the gain after going from 4 regular narrows to 2 narrows and the donuts?

[cbergeron]

I drive very consciously and safely with these wheels during this experiment. The rear of the car definitely 'boat tails' at high speed, so I can't go above 55 with this configuration. I never go that fast during my commute, so it's not really an issue (unless I'm coasting down a big hill and trying to get up as much speed as possible for coast).

Well, after thinking about it more, by adding these skinny wheels netted out less of an increase than I previously thought. For one thing, these wheels aren't broken in yet. More importantly, by replacing the wider wheels with narrower ones I've created a gap in the rear wheel well that acts like a parachute.

During this most recent tank, I did a wiper delete, passenger mirror delete and replaced a major trim piece on the passenger door. I have a feeling that those mods netted my higher MPGs and the skinny wheels netted out even.

I think I'll see a significant increase when I install rear wheel covers.

Tripleskate: Suprisingly, aside from more sensitive steering, the ride isn't much different. It rolls nicely and they make a neat whine sound that sounds like an electric motor. It's very subtle, and I actually like it - considering that one day I'd like to convert this bird to an electric.

[cbergeron]

I'm hypermiling for fun, but it's tricky because there are so many X factors: other drivers, traffic lights, school busses (got stuck behind one today, ugh), etc.

It would be neat to see the effect of my changes in a lab environment, but I'm having fun with it as it is. I just bought a Honda Insight, so it should be fun playing with that once it gets here.