I've heard the size of your wheels affect your mpg.

[whyified]

Is this true? And in what way?

[00zx2s/r]

it shouldn't. I know that it will affect your mph...

[AZN_ZX2]

It will throw off your odometer as well as your speedometer. Haven't heard anything about mpg though. Maybe since it affects your odometer it will make the mpg number when you calculate it end up being wrong

[00zx2s/r]

^^^that could be

[whyified]

Hmm, how would it affect my mph?

[AZN_ZX2]

Cuz the wheel size is changing. If your asking for a more in depth explanation hopefully someone else will pipe in. I imagine the same way it would affect the odometer.

[rusty]

Its not how big they are, its how you use them.

[AZN_ZX2]

Its not how big they are, its how you use them.

lol what

[00zx2s/r]

ya rusty that makes no sense wuts so ever...

[AZN_ZX2]

He was joking noob. And stop following me in threads lol

[00zx2s/r]

I'm not following u. I posted first!

[00zx2s/r]

* oh ya.... lol.! hahah forgot to add that. And yes I got that he was joking. or atleast I hope he was... haha

[ImCrazy]

the over all size of the tire circumference or diameter effects Mph, mpg can be effected by wheels I suppose of you got some heavy ass wheels your mpg would get worse.

[Sir William]

It will throw off your odometer as well as your speedometer. Haven't heard anything about mpg though. Maybe since it affects your odometer it will make the mpg number when you calculate it end up being wrong


Bigger wheels do not = wrong readings on the speedo.

If you calculate the total diameter of the wheel and tire, the trick is to keep it the same as stock.

In other words... Larger rim.... smaller sidewall.

If you get a bigger wheel and a higher sidewall or a sidewall close to stock, yeah it will be out.

[AZN_ZX2]

Bigger wheels do not = wrong readings on the speedo.

If you calculate the total diameter of the wheel and tire, the trick is to keep it the same as stock.

In other words... Larger rim.... smaller sidewall.

If you get a bigger wheel and a higher sidewall or a sidewall close to stock, yeah it will be out.

Hm I coulda sworn thats what was being said on the old site but oh well. I see your point though

[rusty]

the over all size of the tire circumference or diameter effects Mph, mpg can be effected by wheels I suppose of you got some heavy ass wheels your mpg would get worse.

Its called GIRTH

[ZX2 S/R Black]

All that needs to be posted is this link http://www.miata.net/garage/tirecalc.html
:)

all you have to do is type in your stock size... and your aftermarket size, then it will show you the difference... I have 215/40/17's they are almost the exact same...

[Sir William]

I was just going to post one....

It didn't work with my machine and I don't feel like downloading the program to use it..... so if that happens to you try this link.

http://www.dakota-truck.net/tirecalc/tirecalc.html

[ZX2 S/R Black]

here is a quick few I'll post that are close enough...

stock:
185/60/15

Next size... S/R has
205/55/15 supposedly the miata site says that's .6% off compared to stock... so since Ford went .6% off I will post rim/tire combos that don't exceed that


15" rims
205/55/15 .6% off stock
225/50/15 .5% off stock
245/45/15 .2% off stock won't fit without spacers...

16" rims
215/45/16 .5% off stock
245/40/16 .1% off stock won't fit without spacers...

17" Rims
215/40/17 .1% off stock
245/35/17 same as stock won't fit without spacers...

[Apex]

If the car is assumed to travelling at a constant speed, then the car would cover more ground per crankshaft rotation with a larger wheel. This would mean more MPG. The gains would be minimal of course.

[wifeszx2]

Larger diameter wheels/tires equals more rotating mass equals less MPG. However, smaller diameter wheels/tires equal better MPG city, but less MPG highway. Larger diameter wheels/tires equal less MPG city but more MPG highway. You would have to drastically change the numbers to really notice it though. Changing from stock 185/60/15 to 195/55/15 or to a 205/55/15 wouldn't be very much. It will only throw your MPH off by about 1mph too. I was running 205/50/15 at one point and my highway MPG decreased from 37-38mpg to 35mpg. When I was running 195/55/15 I still got 36mpg highway.

[iceracer]

Since the "indicated" miles will not change, if you go by your odometer the mpg will not change. If you are driving a measured distance and judge your mpg by that, then yes a slight difference in mpg would be shown.
As has been said, it is not the size of the wheel but the size of the tire on that wheel.
I think I posted much the same thing on the OLD site, which has been lost.

[mechtech]

Light wheel/tire assemblies can help a bit -braking, acceleration, gas mileage.
Larger diameter wheel/tire assemblies can help a bit.
But a larger assembly will still read the same mileage on the odometer. The car does not know that the tires are larger. So, you could get better gas mileage, but it will not read more [unless it was a lot better].
Get the wheels/tires that you want, and drive sensibly. It will make the most difference by far.

[mellowness65]

the size doesnt really matter, that'll affect your readings though. The weight of a bigger wheel will make your mpg's worse. Would you rather run a marathon in light shoes or hiking boots? Light shoes, because less energy is tied up moving them

[Beodude123]

It's usually the tires you would have to worry about. But yes, it can make a difference. It's the rotational mass. So if you have larger wheels, and they are heavier than stock, it's going to take more power for your engine to turn them.

[iceracer]

Allof the things mentioned will have very little measurable difference.
Just remember the main thing that affects mpg more than anything else. The right foot.

[Team Havoc]

The weight of the rim and tire compo may affect the mpg. More lighter of the combo the the more mpg you will get, and the more the combo weighs the less mpg you will get.

[LiveWire]

Wider tires also reduce MPG by inducing more drag.

[simplicity05]

Bigger wheels do not = wrong readings on the speedo.

If you calculate the total diameter of the wheel and tire, the trick is to keep it the same as stock.

In other words... Larger rim.... smaller sidewall.

If you get a bigger wheel and a higher sidewall or a sidewall close to stock, yeah it will be out.

Does running a lower profile tire decrease ride quality? If so, by how much?

[Beodude123]

It depends on the tire. Jen used to have some tires that were really bad for ride. We switched to Nitto Neo Gens, and the ride improved a lot!

But yeah, it can decrease ride quality. All that sidewall is going to absorb some of the bumps in the road.

[JohnP]

I've been running 205/40/17's about 10 years , same mileage as the stock *, same OD. Ride quality depends on the air pressure you run , 28-30 runs smooth , 38-42 runs rough . Ran Nitto Extremes , changed to Neo Gens , awesome tire wet or dry .

* After the engine was modified the mileage dropped a little down to 32-34 .

[S/R-71]

I think I had 14's on my 98' zx2. Are 15's stock? I know that my s/r has 15's, but I thought that they had 14's otherwise.

[JoshDank]

I think I had 14's on my 98' zx2. Are 15's stock? I know that my s/r has 15's, but I thought that they had 14's otherwise.

14's and 15's were stock, depending on options.

[powder]

185 60/15's = 23.75" dia

205 40/17's = 23.5" dia

Closest you can get to stock dia w/ 17's. JP's right, you won't see a mileage difference.

[ZX2WV]

i always get a little less MPG with my 215/40/17's.

i assume its from friction. because if you have a tire thats a lot wider, that means there is more contact.

thats just what i think.