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

  1. #11
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    Just to clarify one of your final points AeroMPG, you state "RR apparently decreases as width increases". Does this mean that there is a reduction in the rate at which rolling resistance increases as width increases ?

    I've started to lurk my way around the very interesting Ecomodder site in an attempt to make sense out of the raw data such as Kerschbaum's, particularly as it seems to contradict what I've found on the Alto. I won't have the opportunity to replicate the Alto experiment on the Mirage because I don't get to manage and record how it's refuelled and driven. Others will no doubt, and I look forward to seeing the results here.

    Regards to all
    Flange



  2. #12
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    Hi flange.

    Rolling resistance is greatly affected by pressure. If u notice, an under inflated tire runs extremely hot. A lot of heat us actually generated by the sidewall because it moves so much and creates excessive heat.

    Yes, roiling resistance will increase with pressure but not too much because passenger car tires are all radial. The contact patch is controlled by the steel belt which is working very hard to keep the contact patch stable. This is different from bicycles bias constructed tires. Obviously with increased pressure comes less sidewall movement and hence lower rolling resistance. But it also affect overall grip and braking distance as the steel belt will still allow slight deformation.

    That being said, for an equal everything else (pressure, tread pattern, carcass construction, etc), the LRR compound will produce a lower rolling resistance compared to a full carbon black tire.

    If you want to squeeze max MPG, try 100% silica instead of silica blended tires

        __________________________________________

        click to view fuel log View my fuel log 2013 Mirage (Malaysia) GS 1.2 automatic: 44.6 mpg (US) ... 19.0 km/L ... 5.3 L/100 km ... 53.6 mpg (Imp)


  3. #13
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    Interesting stuff thanks Polkiuj. Then of course is the cost of the tyres. As mentioned, the LRR tyres that I costed a couple of years back (Ecopias by memory) were going to cost me well over $700 for a set which (if the OEMs are to be accepted as indicative) would have lasted for 20,000 odd km, whereas the $400 Kingstars gave me around 55,000km plus with the added benefits of dramatically improved traction and better ride.

    The only uncertainty is, why does my real world experience regarding MPG contradict well accepted theory regarding LRR vs conventional tyres. To say nothing of on-road tests such as AeroMPG's roll down tests ? If my experiences had been over a few tanksfull here and there then I would accept faulty method as the reason, but my experiences cover 50,000 odd km.

    It will be interesting to see if others do extended and methodical tests...

    Regards to all
    Flange

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    Well, I really can't answer your question there. As to why your tires are shot by 20k km seems very odd to me. The Alto is a very light car (close to a mirage) and they should be lasting well over 50k (185/65/15 LRR tires would have a projected life of 90k+ on my previous Avanza, I changed car after 50k kms. The tires had 4mm+ of tread left).

    Let me go and measure the tires on my Mirage later (Only have 6k on them though, not really accurate) and will get back to you on projected life.

    Did you have other mods done on the car? Could your driving and fuel saving techniques have improved dramatically? Could it be that Kingstars are actually LRR tires?

        __________________________________________

        click to view fuel log View my fuel log 2013 Mirage (Malaysia) GS 1.2 automatic: 44.6 mpg (US) ... 19.0 km/L ... 5.3 L/100 km ... 53.6 mpg (Imp)


  5. #15
    Quote Originally Posted by Flange View Post
    The only uncertainty is, why does my real world experience regarding MPG contradict well accepted theory regarding LRR vs conventional tyres.
    I think it's certainly possible to see exceptional results like yours that contradict the general rule. But I'd be reluctant to say the lesson from that single experience means the well accepted theory isn't generally right.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage ES 1.2 manual: 63.2 mpg (US) ... 26.9 km/L ... 3.7 L/100 km ... 75.9 mpg (Imp)


  6. #16
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    I've done some measurements and calculations yest, although not conclusive (since I only done about 6000 km), the results are very positive. My tires should last about 80, 000 km.

    I think there is some issues if your tires only lasted 20k km.. Possible pressure, alignment, driving? I really don't know..

        __________________________________________

        click to view fuel log View my fuel log 2013 Mirage (Malaysia) GS 1.2 automatic: 44.6 mpg (US) ... 19.0 km/L ... 5.3 L/100 km ... 53.6 mpg (Imp)


  7. #17
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    Here is some interesting reading on rolling resistance from bicycles. I found it hard to believe, but both this article and my own experience suggested that having too much pressure in my wide, slick bike tires actually was slower than having the "right" pressure. Of course, the ride was also much more jarring. I think a fair summary would be that if the tire is so firm it must move up and down with every little bump, that saps more forward momentum than if the tire was able to roll over the bumps deforming a little rather than bouncing. http://www.schwalbetires.com/tech_in...resistance#why

    Maybe the real point is that my assumptions aren't as reliable as good data.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 manual: 45.0 mpg (US) ... 19.1 km/L ... 5.2 L/100 km ... 54.1 mpg (Imp)


  8. #18
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    That's a really interesting find thanks Canoehead.

    But to counter your statement re your assumptions, not all data is good data - queue whispered "global warming".

    Cheers
    Flange
    Last edited by Flange; 06-20-2013 at 07:45 AM. Reason: global warming

  9. #19
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    The cold hard facts on it.

    But but but, 14's look so terrible. /sadface
    Daily: 2017 Mirage G4 SE - Not Boosted Yet!

    Current Project: Working on legitimate Mirage Tuning
    .

  10. #20
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    Canoehead, that is excellent reading BUT, and it's a very important but. Bicycle tires are NOT the same as car tires. Simply because bicycle tires are bias (cross-ply) tires while our passanger car tires are of radial construction. A quick googling will tell U the difference =)


        __________________________________________

        click to view fuel log View my fuel log 2013 Mirage (Malaysia) GS 1.2 automatic: 44.6 mpg (US) ... 19.0 km/L ... 5.3 L/100 km ... 53.6 mpg (Imp)


  11. The Following User Says Thank You to Polkiuj For This Useful Post:

    Canoehead (06-20-2013)

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