Testing rolling resistance of the Various Tires of the Suzukiclone Fleet (RE92 wins)

[Olympiadis]

Which ones are these?

[niky]

Look like first generation (NA) Miata wheels, to me.

[Olympiadis]

Originally Posted by niky

Look like first generation (NA) Miata wheels, to me.

Do you know what these weigh?
I don't have any Miata wheels yet but I am considering them if they will fit a Ford Focus.

[niky]

About 12 lbs each. Should fit if the PCD is the same, but our Focus is different from yours, so I don't really know.

[rmay635703]

Well, I had a few issues with this thread from the getgo so I figured I would post my scientific (lol) set of data points for comparison on another totally different vehicle.

In any event my testbed was a Miles ZX40 EV, its top speed determined by the 48v motor and single gear is 30mph summer and 28mph winter (clean road)

I did a test in front of my folks house to see how far the car would coast from 5mph to a stop.

I tested the stock Powermax 769 - 155x65r13 and some randomish Honda 115x70x14 space savers, last year at this same time I was running some antique Goodyear continentals 155x80r13's and will include a bit of antidotal from them. All tires were tested at 60psi. I did want to test some 125/80r13's (because I have always had excellent luck with them) but I had none that fit the miles lug pattern.

In any event on flat ground and a huge 30 degrees, wind was nearly calm with a couple MPH here and there with a very thin layer of slime on the road

Powermax 769 155x65r13s coasted a whopping
35' 3" (both runs were only a few inches off, must have been dumb luck) These are the stock tires from miles

Honda 115x70r14 space savers on front only a whopping
39' average (1' variation, 2nd run was further)

I then tested top speed, unlike any other vehicle on the road the Miles ZX40 cannot change gears or increase power output and tire changes are easy to test based on WOT top speed.

Results
Powermax - 28mph (on the normal stretch we run everyday)
Spacesavers up front - 29mph (same place)
Old Goodyears - 29mph (speedo corrected but also at 5-10% higher energy draw due to the size change no doubt)

So given the set of tires I have available I noted no significant difference besides a bit of traction difference and of coarse some major road noise on the spacesavers (rather agressive tread for a bald tire actually).

Also before size is brought up although the space savers "should" be a smaller diameter (1/3") I did note the car sat higher because the tires are more like old balloon tires, car sat a bit higher on the space savers than with the regular tire and side to side comparison off the vehicle same deal, look more like moped style tires. It is also worth noting that the car is about 2400lbs and actually has a tad more weight to the rear.

Ah well. When summer comes along maybe I can do a more convincing test with clean roads and warm temps.

Something worth noting is that the Miles Zx40's alignment is not significantly affected by the space savers, I have noticed some space saver designs when put on my cobalt or commuta caused visible deflection due to the really strange offset on the rim, I would think this would have more affect on how far you coast than the RR because it messed up your alignment. But I digress.

Happy coasting.

[MetroMPG]

Happy coasting indeed!

After 4 years, I finally got around to sticking the "winning" Bridgestone Potenza RE92's on the Firefly. (Because the car that was wearing them -- the ForkenSwift electric car, top photo this thread -- was retired last year).

Despite the presumably worse aero of the slightly wider tires (165 vs. 155) plus air-blender alloy wheels vs. the car's stock, smooth-ish 13 inch wheel covers, the car got much better mileage on a round trip (back roads) to a cottage:

• 76.8 mpg US (Goodyear Invicta) round trip
• 82.5 mpg US (RE92) round trip

Notable: that was with a 3.2 km/h (2 mph) higher average speed on the RE92 trip. (Similar weather & traffic conditions ... mostly deserted back roads driving, 87 km / 54 miles round trip.)

(Note: the RE92's have a ~1.4% smaller circumference than the Goodyears. I didn't apply this correction to the speed/distance figures here. Even corrected, the MPG % difference is much larger than the measurement error.)

Most of this was driving with load (DWL) on rolling terrain, but I definitely made use of the obviously better coasting ability of the RE92's when approaching most turns & stops (engine off).

Of course, in fairly typical ecomodder fashion, I changed more than one variable: the car also has a brand new air dam on it. So I can't say how much of this improvement is from the tires alone. It seems unlikely it's all from lower rolling resistance. (But I plan on A-B-A'ing the air dam...)

[MetroMPG]

Oh, and PS:

I really like the look of those wheels on the car. But I'll be covering them up with smooth wheel discs soon.

[Daox]

I agree, it looks nice with those wheels.

Nice MPG too!

[freebeard]

I got a new set of wheels and I'm thinking, given the cost of unmounting and remounting, and mounting the new ones, I might just as well get a new set. They're 15s.

I checked the Portenzas and they are only available in one or two sizes in 14-, 17- and 20". The front tire I'm rolling now is 165/50R15 Federal Formosa FD-1, with the stock 165(70?)R15s on the back. I'd like to find a LLR 15" tire with that 50(or55)/70(or 80) split in aspect ratio to preserve the drive axle gearing. Any suggestion?

I was hoping my next set of tires would be i3 Ecopia 600s, but that takes a 4x19" wheel.

[2000mc]

Originally Posted by freebeard

I checked the Portenzas and they are only available in one or two sizes in 14-, 17- and 20".

The potenzas are lrr in the 165/65-14 size only