How are my wheels impacting FE?
 

Long story short I have a 2000 Civic LX I bought used this month with 160k on it. Did timing belt valve lash and all that good stuff. I don't have the stock wheels and the car came with aftermarket wheels. I cant link to them because of post count but they are Maxxim Ahead graphite and polished they are 16x7 I think with 205/45/16 tires on them I have at 40psi. My speedo is 5mph off roughly but I have heard this is common on these cars and likely not due to the wheels since they should be almost the same OD as stock.

Only info I found for weight was like 16.7 lbs each and I have no idea what the stock LX wheels would have weighed. I think the wheels impact acceleration due to the low power output of the little 1.6L even with my manual tranny. She hates to be shifted below 2500 RPM and prefers 3k and doesn't like anything but very light throttle cruising at below 2k and can lug and hafe valve noise with too much throttle in that area. She prefers to always be above 2k.

But I think it helps at higher speed by giving me a lower RPM. How much of an impact do you guys think they are having? I don't really want to replace them as the guy has brand new tires on them and I like the handling better than smaller wheels. Do you think the design of them is also bad for aero?

Inspect more mechanical issues before determining the wheel issue, the rim and tire combo is common on a lot of including civics, but some have 15 or 14. Check gear fluid, if there is no dipstick" drain it and fill with the recommended synthic. No cel?? if cel check for solution, also clean maf and iacv.

Those Maxxim Ahead wheels are 5 spoke with large openings between the spokes , and wider than they need to be, so yes, they'll have a negative impact on your fuel consumption.

http://www.konigwheels.com/core/medi...4fea6661884aa6

There are a few threads on the benefits of closed / solid wheel covers.
The kind of tyres you have on them, will have more effect on MPG.

Under 17 lbs isn't all that bad though.

Going smaller / narrower / lighter will only return a profit when you can do it at very little or no cost - i.e. sell the wheels for what the replacement wheels would cost.
It's just about impossible to single out this effect in day to day driving.

You can break even on getting better / lower rolling resistance (LRR) tyres.
I've personally seen a 6.7% reduction in fuel consumption when going to the best available LRR tyres.
If you replace them when the tyres need replacing anyway, you can actually benefit from the change.

Wheels/Tires:
Stock tire size on your car would be 185/65/14, or 23.4” diameter. Your 205/45/16s are 23.2” diameter, so less than a 1% change. The downside is that most low profile tires like you now have are geared more for grip and performance, not for rolling resistance.

For example if you wanted to go with Michelin Energy Saver A/S the smallest tire for a 16” rim on Tire Rack is 205/60/16, which is 25.7" or 10% bigger. I know from experience there is a drastic change in acceleration when you upsize that much, if you even can fit something that large on your car without rubbing.

As far as handling goes, my Celica had fairy new low profile Kumho 205/50/16s on it when I bought it. When I replaced them with oversize 205/65/16s Michelin Energy Savers the handling of the car surprisingly improved drastically. Night and day difference, they were better on dry pavement, wet pavement, cornering, everything except squealing. It was simply a better tire, and that advantage overtook the fact that the previous ones were low profile.

If you like the wheels and want to run them, go for it. If you are looking for aero, personally I think the 7 Slot 15x6 inch, 4x100 bolt pattern (45mm Offset), One Piece Alloy Factory OEM Wheels look pretty good and appear more aerodynamic. Keep an eye out for a pair cheap. Pair that with some 185/65/15 or 195/65/15 Michelin Energy Saver A/S tires (or your LRR of choice) and you would have a good factory looking LRR setup.

Engine:
Your 1.6L was designed to be a mainly high revving engine, low end torque was never the specialty of semi-modern four banger imports. My celica hates below 2k as well.

Gearing:
What are your cruising RPMs right now at your most common speeds? I regeared my Celica because my highway RPMs were 2900@65 and my interstate RPMs were 3600@80. Now I sit at 2600@65 and 3100@75 (great mod btw, 80->75). I wouldn’t recommend you significantly regear like 10% using tires unless your RPMs are way too high, as you take an aerodynamic hit, the weight increases, etcetera. If your RPMs are already decent, going up 3-4% would help without significant impact.

OT: aardvarcus, did you post a thread about regearing your Celica? I'd like to feature it if you did, and if you have MPG before/after results.

Back on-topic...

Here's a real world example of how wheel/tire choice affects fuel economy. The new Mitsubishi Mirage is available in only 2 trim levels in New Zealand, with the only difference being wheels/tires and convenience options. Engine/drivetrain is identical.

The functional difference is in wheels/tires. (14's on the base, 15 on the fancy model):

Base car:

http://mirageforum.com/forum/attachm...1&d=1361669610
165/65R14

Uplevel car:

http://mirageforum.com/forum/attachm...2&d=1361669634
175/55R15

The base car's MPG rating is 6% better than the other car, due to a combination of:

• slightly narrower tire on the base car has a slightly better drag coefficient and smaller frontal area
• that flat plastic 14 inch wheel cover on the base car is more aerodynamic than the open spoke alloy wheel
• the different tires probably have different rolling resistance coefficients
• the bigger alloy wheels & lower profile tires may have more of their mass concentrated further away from the rotation axis, which need more power to accelerate

Not just speculation -- the impact of wheels/tires on MPG was confirmed by the manufacturer.

From: How wheel & tire size and style affect Mirage fuel economy/mileage

But the bigger ones look faster! :D

True. You just can't put a price on sexy.

If the outer diameter is the same as the stock configuration the aftermarket wheels are not giving you a lower RPM.

The stock wheels and tires are probably heavier than your current configuration. 16 pounds is pretty light for that size wheel. You could go lighter with a 14 or 15 inch wheel, for example the Civic HX wheels.

Whats probably hurting is the width of the tires. The tires also might also have more grip than stock or LRR tires.

I agree. Those wheels and tires are definitely holding back FE, for all the reasons cited above.