Experiment: coast down distances (rolling resistance) @ various tire pressures

[CapriRacer]

Originally Posted by MorphDaCivic

Thanks for posting and running the test. Has anyone had a blowout from running pressures exceeding the tirewall max?

Yes, there have been reports of blowouts, as well as other issues - groove wander, uneven wear, etc. Spend some time searching this web site and you'll find them. BTW, other web sites have also reported similar issues.

[dcb]

where was there a report of a blowout because of extra psi?

[cdltpx]

Ideally you would want to conduct the test with the measuring device attached to the rear bumper rather than trying to hold it while trying to drive. Each time you pull the wheel to correct off coarse you add drag to the vehicle and affect the test results. I located a yourg man on you tube screen name=(landongendur)= that did some test with his metro. He took the mirrors off tested. He took the regular tires off and used 4 spare tires test vs regular. He ran vehicle with hatch back open test vs closed. He did speed test you name it if he thought of it he posted the results on youtube.

[MetroMPG]

More inflation vs. rolling resistance data for the pile.

It matches the previous tests (meaning, rolling resistance decreases significantly up to a certain pressure, then plateaus).

Tire tested: Bridgestone Potenza RE92 LRR tires in 165/65R14 size (Honda Insight OEM tire, installed on Geo Metro electric car - ForkenSwift)




Weather: 25C, 8 km/h SW wind (test course ran NW/SE)

Methodology:

• tires were pumped up to 70 PSI, drove to test route (< .5 km), pressure adjusted
• car was reversed up a small hill (approx. 2 ft. elevation) and stopped at a marked point
• hand brake was used to stop - hydraulic brakes were not used at all during the test or on the short drive to the test area
• transmission in neutral, hand brake was released
• car rolled down short hill onto a flat run-out area
• where the car stopped, the road was marked
• pressure was adjusted (dropped 10 PSI)
• rinse & repeat

Results:



For kicks, see also: comparing RE92's @ 50 PSI to space saver spare tire donuts @ 70 psi - http://ecomodder.com/forum/general-e...donuts-70.html

[euromodder]

What's the rated tyre pressure for those tyres ?
Looks like there isn't very much to be gained by going beyond 40/50 psi

[MetroMPG]

44 PSI... and I agree, that's what it seems to show.

[MetroMPG]

Originally Posted by cdltpx

Ideally you would want to conduct the test with the measuring device attached to the rear bumper rather than trying to hold it while trying to drive.

Tests were done in a straight line with start/end points marked on the pavement. No handheld/bumper mounted instruments required!

I located a yourg man on you tube screen name=(landongendur)= that did some test with his metro. He took the mirrors off tested. He took the regular tires off and used 4 spare tires test vs regular. He ran vehicle with hatch back open test vs closed. He did speed test you name it if he thought of it he posted the results on youtube.

Yes, that's "Peakster" - a member here (you can search for his posts). He cut way back on driving, for the most part, so hasn't been around in a long time.

[Arragonis]

Are you going to try the reverse, 'normal' tyres on the insight ?

[MetroMPG]

Nope!

I learned what I needed to learn from this test & the comparison of all the tires in the Suzukiclone fleet - RE92's at around 50 PSI are my best option for LRR.

[silverinsight2]

Originally Posted by MetroMPG

Nope!

I learned what I needed to learn from this test & the comparison of all the tires in the Suzukiclone fleet - RE92's at around 50 PSI are my best option for LRR.

Something confirmed again and again at Insightcentral. Thanks for adding some science to it.