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

[Zero]

The Japanese Mirage 1.2G is equipped with 175/55 R15 and the other models use the 165/65 R14 tires.

http://www.mitsubishi-motors.co.jp/m...de/gra_01.html
http://www.mitsubishi-motors.co.jp/mirage/

[cinder]

Here's a Tire Size Calculator . https://www.tacomaworld.com/tirecalc...5r15-185-60r15 .

[mightymirage]

I like 14 inch tires, cheaper! But the Mirage tire size is hard to find, Not sure if little wider tire will have better handling

[cyclopathic]

I like 14 inch tires, cheaper! But the Mirage tire size is hard to find, Not sure if little wider tire will have better handling

It will. We are running RT-43 in 185/60 on stock wheels and they are huge improvement in handling. MPG will suffer.

[inuvik]

It will. We are running RT-43 in 185/60 on stock wheels and they are huge improvement in handling. MPG will suffer.

That's why I hate to admit it, but other than upgrading to the 14x6 Oz Racing WRC's I'm gonna stick with the OEM Enasaves or the Bridgestone Potenzas

[cyclopathic]

That's why I hate to admit it, but other than upgrading to the 14x6 Oz Racing WRC's I'm gonna stick with the OEM Enasaves or the Bridgestone Potenzas

Completely understandable. However with Enasaves you may be saving fuel, but not money. Here is a case study:

Enasave
Cost: $95+$12+$16=$123 per tire (price, shipping and mount)
Treadwear 340, life expectancy 40k
cost per 1,000mi $12.3

RT-43
Cost: $58+$12+$16=$87 per tire (price, shipping and mount)
Treadwear 600, life expectancy 70k
cost per 1000mi $5

So tire savings $7.3 per 1000mi. The difference in MPG btw both is ~1.25gal per 1,000mi.
EDIT: changed to 40MPG avg as a base. So gas has to be ~$6/gal to break even.

The other side effects are better grip, especially in wet, and shorter range (which is already too short).

TireRack prices were used for consistency, and offered rebates were not included. RT-43 common tire, it can be purchased and mounted at local Walmart $64+$14+tax

[inuvik]

Good info, be interesting to see how it affects your mileage long term. Keep us posted. My plans are rims in 2016 and tires in 2017.

[deleted user]

1k miles takes about 18 gallons for me. Looks like you need 22. That's 4 gallons or 8 dollars per 1k. $800 PER 100K means two sets of tires for free, but when you figure $160 for 4 Ensaves then that leaves $640 cash in my pocket.

For me the Ensaves work perfectly and based on the measured wear of 12.5% front and half that on the rear at 10k miles, they might even get me 60k per set before they will not pass inspection.

Running 50 psi with perfectly even wear across the 3 grooves per tire.

I'll repeat myself, changing tires without proper alignment is doing it backwards. Even if your alignment is within the ridiculously generous specs, it's still responsible for increased tire wear, and I do not drive that slowly.

Hopefully Mitsu will address the rear axle issue in the 2017 model and help those without the skills to correct alignment themselves.
Maybe I'll get around to adjusting the left side camber to close to the right side's .7 degrees and keep the toe at 0.

regards
mech

[cyclopathic]

I am not sure what the actual MPG loss on RT-43. They are definitely not LRR tire, but as non-LRR go they are not bad. Consumers tested them and found them rolling better then average; I think tirerack has some data. My son drives Mirage, and your consumption cannot be compared directly. Different conditions, different speeds, different driver, 10% alcohol in our gas. The estimate was made under assumption of 20gal per 1k and 5% loss in MPG. If you use 25gal it will be 1.25gal.

As far as LRR Enaseve are very good. In similar comparison of RT43 and Michelin Energy Saver loss was ~3MPG, or about 5%. They do grip good, esp in wet and light snow. We get more winter than you but not enough to justify dedicated winter tires, so it is a piece of mind. Not saying that one is better than other, just a choice. If you're driving 10K a year, you'll be replacing tires in 3-4 years anyways, so long treadwear is not a factor.

[cyclopathic]

Even with closed wheel (ie. conventional) bodywork, the drag effect of wider tires is significant:

From: Influence of the tire width on drag, lift, and yawing moment, after H Kerschbaum Fig 5.72



CD --- tire & rim size (for a 1991 BMW 318i)

0.293 --- 155 R 15; 5 1/2 Jx15 St. with wheel covers
0.294 --- 165 R 15; 61 2 Jx15 St. with wheel covers
0.297 --- 175/70 R 15; 6 Jx15 St. with wheel covers
0.305 --- 185/65 R 15; 61 Jx15 St. with wheel covers
0.311 --- 205/60 R 15; 61 2 Jx15 St. with wheel covers
0.314 --- 205/60 R 15; 7 Jx15 LM
0.319 --- 225/55 R 15; 7 Jx15 LM

Keep in mind the increase in Cd comes with an (admittedly small) increase in A (frontal/projected area) too, so you're getting a double whammy.

Data for other vehicles (source):

• 1986, wind tunnel development work for Subaru XT show a drag increase of 5.1 % when tire size is increased from 155 to 185 series radials.

• 1984-1987 HONDA CRX shows jump from 165 to 185 series radials increase drag 9.3 %.

This is all complicated by the fact that if you hold everything else constant (tire construction & materials properties), RR apparently decreases as width increases. So the net impact on efficiency by going with a wider tire will depend on whether you primarily drive fast or slow.

Just to add to wonderful posts by Metro, given the same width and outer diameter, lower profile tire will have higher rolling resistance. Big portion of RR comes from sidewall flex, and lower profile tire will have more flex/more heat generated in sidewall. This is why over-inflating tires help to improve MPG, but only to certain point. At higher pressures the sidewall flex decreases, but at some point increasing pressure does not reduce flex significantly. Meanwhile the losses in thread and rolling over cracks/potholes/bumps will increase as tire cannot absorb them.

I suspect the difference btw 14" and 15" in OP comes not from marginally increased Cd, but from different brand of tires and tire lower profile.