Why do economy cars have such tiny tires?

[wildmanjoe]

Every time an automaker makes an economy car, they always give it short, fat tires; giving it a look that was pulled off much better by the BMW Isetta.

Yet every time a you look at a car that's built for a mileage competition, you see tall, skinny tires.

Given the lower rolling resistance, higher final gearing and better traction of tall and skinny tires, why don't more manufacturers use them?

[balthazar]

Those purpose-built MPG rigs have 1 goal only- MPG. Ride comfort, traction, handling, etc doesn't even make the list.

Besides, low-profile rubber band tires are considered 'sporty'; tall skinny tires look cheap/puny.

You knew all this, tho, WMJ.

BTW, the Fit wears 16"ers, the Isetta wears 10"ers. Even as a vintage guy, both seem appropriate here. Isetta is what; one-third the size of the fit?

[wildmanjoe]

The low pro's nowadays already let the driver feel every bump, dip and dead prostitute in the road, so ride couldn't be that much worse. I see WRX's with tall and skinny tires driving around here in the winter from time to time as well. Even if the tires were wide, a taller one would mean fewer revolution per mile and better mileage, at least in theory, plus the advantage of the car not looking like a pregnant rollerskate.

[balthazar]

wildmanjoe ~ >>"The low pro's nowadays already let the driver feel every bump, dip and dead prostitute in the road, so ride couldn't be that much worse."<<

True; a byproduct of short stiff sidewalls. However, all the rags want to preach about is hhaannddlliinngg, as if econoboxes are carving canyons at 2AM X-mas night instead of slogging thru rush-hour at an average speed of 30 MPH.

>>"I see WRX's with tall and skinny tires driving around here in the winter from time to time as well."<<

You see WRX's like THAT driving around? Natch; that's a singular-purpose tire (traction in snow/ice), it has zero business in real world commuter conditions. Aren't a lot of them steel-studded, too?

>>"Even if the tires were wide, a taller one would mean fewer revolution per mile and better mileage, at least in theory, plus the advantage of the car not looking like a pregnant rollerskate."<<

Now we're talking about lesser distinctions.

A '12 honda Fit "Sport" wears 185/55 R16s, which are 24.0" tall. If it were a -say- 185/75R16, it would increase to 26.9" tall. What this does effectively is reduce the final drive ratio, making the vehicle accelerate slower. The previous tire change would reduce a -say- 3.25 gear to 2.89. Now you have to swap gears to retain the original acceleration rates, which decreases MPG in gears below 1:1 / OD. On top of that, a 75-series tire here will only set the rag jockeys a-moaning and a-whining about the hhaannddlliinngg (the taller tire will also be heavier, increasing unsprung weight, also affecting handling). Compromises.

Rims on average have of course gotten taller & taller over the last couple decades. Overall tire heights have conversely gone down quite a bit. A 1960's 8.25x15 equates to a 205/80R15, which is 27.9". I don't believe that's at all commonplace on cars today- a LaCrosse for example wears 235/50R17s : 26.25" tall.

All that aside, I get your point; you're wondering on getting narrower tires on the smaller cars, instead of the mini-steamrollers the "Sport" models often have. I could see that as long as overall heights didn't move much- so they'd have to get narrower. THAT WAY, they'd be lighter, have lower rolling & wind resistances, and retain all performance stats. Handling at 75% & above would decrease, but not as much as the above scenarios I posted. At this level of distinction, I believe it boils down to marketing/perception ("fat tires look cooler/handle better").