The protege comes stock with decent tires (as far as OEM compact cars go...). Now the EPA 25 city/31 highway ratings are given considering those tires. Has anyone tried to change the tires to a smaller lower rolling resistance tire? Maybe something in the 185 width range...Obviously this negatively impacts handling and braking but it also increases both city and highway gas mileage. My wife drives the protege and our new house will increase her daily driving to 90 miles to get to work. Anybody, who uses their protege for long commutes, bother to record the impact on highway gas mileage of switching to thinner tires?

I'm guessing that a performance enthusiast forum is going to lack any people willing to do this but I figure I would try anyways...besides we can always put performance rubber on a spare set of wheels for autoX.

 

Hey Dude!

I didn't do the wheel/tire swich, but I drive about 170 miles round trip to and from work. I got about 6 Mpgs out of a $40 eBay Short ram intake. That helps get me to almost 40Mpg.

Hope that helps

 

as long as you make sure you don't decrease the overall diameter of the tire, it should help you. if you increase the overall diameter, your mileage should go up on the highway and your revs will fall, but keep in mind your speedo will read lower than your actual speed.

i dunno...the new protege is not exactly a fuel miser. my best hwy mileage has been 32, and that happened once. 29 is my avg fuel economy, 23-24 in typical commuting.

 

icreasing the size of the diameter will only be significant as far as revs falling if the diameter is increased a bunch. going with a +2 setup (meaning a 195/55 or 60, can't remember how it comes out exactly) will knock your speed to about 62mph or so with your speedo reading 60, which will not effect the revs significantly...Also MPG is not effected by engine revs as much as the throttle positon changes and frequency...So lowering your gearing to be going 60 at a lower RPM will not effect MPG as much as some people think, with the same driving style...I had a lack of 5th gear in my last car (it was out of commision) so I had to use 4th on the highway. I had gained about 1400 rpm at cruising speed, but didn't loose mileage as much as I thought I would. I only dropped about 3 mpg average without changing the way I would accelerate around town...that being with a much more significant rev change...

Like you said this is only going to change highway driving anyway. And the increased weight of these tires will make you loose city MPG averages...and possibly hurt highway MPG too...

Your best bet would probably to go with a good hard touring tire. it will not help handling, but the lack of road grip will give a very easy rolling tire, the tire wieght will not hurt city MPG...

 

I'm guessing a narrow tire does improve fuel economy, all other things being equal. I ran 185/65R14 Kumho snows during the winter (bare roads most of the time), and got around the same mileage as the stock 195/55R15 stock Poortenzas.

Considering that snows typically result in worse fuel economy, my theory is that the narrower tread offset the higher rolling resistance.

Not the best proof, but it's something.