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Replacement tires - upgrade questions

Discussion in 'Prius c Fuel Economy' started by mnaf, May 14, 2012.

  1. mnaf

    mnaf Junior Member

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    Trying to plan ahead...
    I've never really deviated from stock size tires on my vehicles, mostly to keep the speedo and odo in order; but the lack of suitable replacement tires for the c (at this time) and the need to order 16" or 15" wheels are making me look at all options. The 15"'s turning circle is awesome but the 16"''s 195/50's must handle great. (can't find a c4 w/ 16's to test drive yet...)
    So....
    It looks like a 185/60R15 like the LRR Michelin Defender might be a good choice if you needed to replace the stock 175/65R15...?

    It has a odometer difference of -0.9% - the odometer would read 100091 miles for every 10000 traveled and the speedo reads 61mph while traveling at 60mph. I recall a thread here about the c's speedo discrepancy but I can't find it (I think the speedometer readout is 1-2mph over real?).
    Is this too much difference or is it really negligible and I should forget about it?
    The 16"'s have a few replacement options but none in LRR at this time.

    I'm driving ~80% hwy (70-75mph) and 20% city; 1500 miles/month.

    Comments? Have I overlooked something obvious/important?
    Thanks.
     
    #1 mnaf, May 14, 2012
  2. rjdriver

    rjdriver Active Member

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    The Michelin Defender looks interesting. No test at Tire Rack yet, and only a few user reviews, all with low mileage, but it looks promising. A 90m mile tire with good grip and wet performance AND low rolling resistance -that would be a sure winner.
     
    #2 rjdriver, May 14, 2012
  3. F8L

    F8L Protecting Habitat & AG Lands

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    A 185/60/15 will likely increase the speedo error beyond the factory built in error of 1.5- 2mph. If you can live with this, want a wider tire, and dont mind a small mpg hit then go for it. :)

    In either the 175/65/15 or 185/60/15 you have a few choices in LRR tire. Personally I would not get the Defender unless you are able to get the $70 Michelin rebate. If you do then it puts them in the same price range as the AVID Ascend. We know how well the Ascend (85,000 mile warranty) performs but we are still in the dark with the Defender. The EP422 (65,000 mile warranty) is pretty decent for mpg and relatively cheap if you get the $70 Bridgestone rebate but it doesn't perform as well as the Ascend.
     
    #3 F8L, May 14, 2012
  4. mnaf

    mnaf Junior Member

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    185/60R15's will result in a speedometer reading of 61mph while traveling 60mph. So that should reduce the built-in error to ~ +0.5 to +1 mph. Reducing the sidewall by 0.1" isn't huge - and maybe not noticeable - but combined with +10mm width, there should be some noticeable difference with 185's.

    I don't know much about Acends - I recall that Yokohamas have (had?) a tendency to wear fast in normal rubber. I was a big Pirelli fan but was won over by Michelin P/S and now Michelin Energy. I'd like to think that the Defender would follow in some of those footsteps.
     
    #4 mnaf, May 15, 2012
  5. F8L

    F8L Protecting Habitat & AG Lands

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    Are using a generic number from something like 101tires or are using values from a specific tire? Revs/mile can vary quite a bit from tire to tire in the same size so I find it hard to pin down a value unless you know the specifics.

    The smaller tire will increase the speedo error so it may read 62mph to 63mph when you are truly traveling 60mph. Using your figures. If you have an OE tire with low revs/mile and chose a tire with the highest revs/mile in that next size class the effect can be noticeable. When I swapped from the 185/65/15 848 revs/mile to a 215/45/17 844 revs/mile the 2mph speedo error was reduce to about 0mph - .5mph too fast. I'm not certain that the revs/mile listen is correct for either tire but taking photos of the height difference made it quite apparent the 17" tire was much taller despite being listed as 24.7" vs. 24.5" on the 15".


    I've heard similar reports from just about every brand. These preorts are usually the result of someone driving aggressively and/or living in a climate not conducive to tire longevity. Their road conditions could also be suspect. Regardless, the manufacture offers a treadwear warranty so if a tire like the Ascend doesn't last the 85,000 miles it is warranties for at least you have some recourse. :) Just read the fine print! Haha
     
    #5 F8L, May 15, 2012
  6. mnaf

    mnaf Junior Member

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    No, I was using generic numbers not specific. I was using numbers provided from:
    Tire size calculator
    I understand that there are brand variations in size.
    Because I'd be cautious about the c's potential tire rub, I was sticking to a moderate upgrade rather than a jump to, say, xxx/50's in the 15" size (while maintaining the speedo difference).

    I usually prefer to buy the stock "performance option" and deal with those sizes. With my current 215/50R17's, the tires will often outperform my driving (but I'm catching up on them) ;) Hence, the decision with the c's 15" vs 16".

    Yeah, there's a lot of subjectivity with tire wear; and I tend not to believe most of it (questionable tire pressures and road conditions). However, by and large, a fair amount of performance Yoko's seem to have that reputation. Having said that, the Acends have an impressive warranty at 85k and if their performance is (even) decent then they'd deserve a chance.
    I rotate pretty religiously - every 6k - and check pressure much more to get the most out my tires. They're too expensive!
     
    #6 mnaf, May 15, 2012
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  7. pubby

    pubby Junior Member

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    Your stock is 175/65R15? On my end they have 185/60R15 as stock :eek:
     
    #7 pubby, May 15, 2012
  8. cinder

    cinder Member

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    The other 1/2 drove the '11 FIT with the recently installed Ecopia 422 ( 36 p.s.i. ) to work in the hard rain and wet roads to report back they did quite well . The display is showing 39 m.p.g. and this is the 5 speed auto . Picked them up for under $59 each ( before tax ) . Got them through a GM parts department and put on by their service center due to the $100 discount from GM . Continentals ( Eco Plus ) are included . Sale ends May 31st . Parts department matched the internet price at Tirebuyer . There's a chance that not all GM parts will be willing to match internet price . May want to call first to get a price match . The Fits tires are same size ( 175/65-15 ) as the C and 2012 Yaris .
     
    #8 cinder, May 15, 2012
  9. cinder

    cinder Member

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    Ford has $100 off until end of June (?) . Yokohama ( Avid Ascend ) are one of the tire manufacturers included . Good time to buy . Who knows what the future holds .
     
    #9 cinder, May 15, 2012
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