Civic Mileage

[Twerp]

Okay, so this is the thread for my 1991 Honda Civic DX.

I'll start right off with the question... How the hell could anybody get the 29mpg avg EPA rating out of this car? Maybe I screwed up the research, but I'm almost sure that the revised EPA rating is around 29 MPG. Even going by the old EPA ratings, I can't believe anybody could average 33 mpg out of the car.

Without doing any fancy driving, or ecomods, even with only doing minimal work to get the car just barely roadworthy, I managed to get around 46mpg. Something is odd here... I think I should be getting closer to 38 mpg with the driving I've been doing. I'm not complaining, mind you... I'm just trying to figure out why I'm doing so much better than I expected.

My main theory is the tires... Right now I have a set of crappy snow/ice tires. The fronts are nearly bald, and the rears have enough tread to make them annoying and impossibly loud. Plus, there's that annoying "clack clack clack" from the ice cleats. I know I have to replace them and I was figuring that they would be destroying my fuel mileage.

In shopping for tires, however, I came to realize that my snows are not the recommended tire size for my car. They are 155-80-13 or something like that. I believe my car takes 170-75-13s. Forgive me if I'm off on the sizes, I'm still learning about tire sizes. Anyway, the snows are way skinnier than what should be on there. I'm wondering if that is how I'm getting my gas mileage.

I'm planning on putting some standard sized replacements on my car, but I might consider going back to a skinnier tire if my fuel mileage goes down significantly. What I want to know is whether running a size too skinny will create any hazards that I should avoid or at least be aware of. Any thoughts?

[Daox]

Skinnier tires will increase stopping distance. I'd recommend going with the skinniest the OEM recommends. That should be a good compromise between stopping power and mileage.

[1.5Ldave]

I have 155/80-13s on my 91 dx and i love them. I didnt really notice any change going from the 175 series except that I can coast noticeable further.

[hondaguy72]

Your roll out distance is causing your actual mileage traveled to read high. I'd guess the correction would be minus 3%....still not bad at all!

[Twerp]

So far I'm happy with the stopping ability of my car... At least, it doesn't appear to be limited by the tires. The brakes themselves are less grippy than I'm used to, but I haven't locked up my wheels (New rotors and the pads are still decent). A swift kick to the brake pedal on my Tundra will jolt me by comparison. The same maneuver in my fiance's Focus will have me getting snuggly with the dash board.

I guess my concern is breaking the bead during hard cornering, but I think I have an easy fix for that... I won't corner hard. It seems to me that the Civic was actually intended to be an economy car, not a high performance machine. You'd never guess that by looking at some of the tuned out Civics out there. My other concern is tire reliability, weight bearing and such, but the snows that are on my car now haven't blown out or anything, and I had a car full of people over the weekend. The average weight per person was prolly 190 to 200lbs times 4 people.

I'll have to see what my odometer says after a trip to work. My truck is calibrated pretty decently and it comes out to about 31 miles or so. If my Honda agrees even partially, I will be satisfied with mileage accuracy. Otherwise I will have to learn to calculate accordingly.

So Dave, are your tires on the stock steelies? If so, I'll prolly go with the 155s. I think I can get them cheaper than the 175s.

I think in the short term, I'm going to pick up a second set of wheels. I'll get some take offs that still have some decent tire meat on them. I've been looking into junkyard inventory for this. Depending on what I get, I might be able to do some A-B-A testing between tire widths at some point in the future.

[Daox]

If you are happy with the 155s and know the safety limits of your vehicle and drive accordingly all the more power to you. Its only when you don't know this that you'll get into trouble. I'm sure the 155s will net you better mileage. BTW, 155s are the stock size for a Toyota Tercel which is only a tiny bit smaller than your Civic. I wouldn't worry about breaking the bead, especially if you have them pumped up good.

[Twerp]

Sounds like I'll be getting some pretty cheap tires then. Sweet!

[Spinall4]

My civic also gets abnormaly good MPG. I do a mixed average of about 80 % fwy and 20 % intown and it does about 44mpg each time. I have the stock tire size in a long wearing tire, a light weight fly wheel, and intake with open element K&N filter.

If I remember correctly there was a thing about Honda admitting to the odometers in their cars recording more millage than they actually travel. I'm not sure how off they were, but it was enough to cause a fuss on the news.

[1.5Ldave]

My wheels are actually aftermarket (came with the car), but are 1/2 inch wider than stock and the 155s still fit. My only regret was not getting them sooner, I love how they handle. Stock tire size is 175/70-13, the 155/80-13s are actually within half a percent of stock diameter so no need to correct on the speedo.

I keep them pumped to 50 psi and they still handle corners great.

To save some money I opted not to get the tires warrantied, since the ones I got were only about $40 each. The warranty would have cost $5 more than simply replacing a tire should one get damaged.