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Installed Lexus CT200h 17" wheels and 205/50/17 tires

Discussion in 'Gen 3 Prius Accessories and Modifications' started by F8L, Sep 18, 2012.

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  1. a priori

    a priori Canonus Curiosus

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    Sorry about the "mushy" tires!

    The FE on the Mustang? OUCH! I didn't take a real measure, but I don't think I drove even 200 miles, yet it took more than 9 gallons of gas to fill up.

    By the way, I just had my first fill-up since replacing my Toyos with the Michelin Primacy MXM4s. As I noted before, there is a clear drop in fuel economy. Of course, the temps have dropped quite a bit, lately, meaning FE would have dropped, anyway. Also, the tires are new, meaning FE also is likely to be lower than with the older tires. The FE for this first tank was 51.0 (on the MFD) or 48.9 by calculation.
     
    #161 a priori, Oct 21, 2012
  2. F8L

    F8L Protecting Habitat & AG Lands

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    So what would you guess you have lost if you take into consideration the weather change?

    The tires are a little less mushy feeling now. Pressure is at 42/40. I'm not sure if I even need to do the split with the 17s, especially XL tires. I'll put the TRD springs on tomorrow. Maybe that will soften the thuds from road irregularities.
     
    #162 F8L, Oct 21, 2012
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  3. a priori

    a priori Canonus Curiosus

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    Setting aside the weather, I'm guessing the drop is about five or six MPG, but I really wont know utill I've had a few new tanks.
     
    #163 a priori, Oct 21, 2012
  4. F8L

    F8L Protecting Habitat & AG Lands

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    *winces*

    Keep me posted. I would expect maybe a 2mpg loss if everything was the same including the wear on the two tires (new vs. new).
     
    #164 F8L, Oct 21, 2012
  5. WE0H

    WE0H Senior Member

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    If you guys get better than my 46 mpg consider it awesome mileage :)

    Mike
     
    #165 WE0H, Oct 21, 2012
  6. a priori

    a priori Canonus Curiosus

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    I'm thinking there is going to be a much larger drop in FE. It took about 3,500 to 4,000 miles for the Toyos to "break in" and start showing top MPGs. Even so, the starting MPGs on the Toyos were much higher. I'm about 4-5 MPG below the starting point of the Toyos, but one tank is too little to show what will happen.
     
    #166 a priori, Oct 21, 2012
  7. F8L

    F8L Protecting Habitat & AG Lands

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    Quick math says that IF you lose 5mpg and IF both tires (MXM4 vs. Proxes A20) were to last 55,000 miles then the MXM4 would cost an extra $150*.

    * assuming fuel price of $3.80/ga.

    That's not so bad for the extra margin of safety, increases handling, better ride etc. etc. :)
     
    #167 F8L, Oct 21, 2012
  8. a priori

    a priori Canonus Curiosus

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    I appreciate the effort to offer financial comfort!

    I don't think the price difference is quite that close. Assuming the Toyos cost $200 per tire and the Michelins cost $150 (my price!!), and further assuming they both would last 55,000 (my Toyos went 60K), the two variables of interest in determining the cost difference between the tires would be fuel economy and the price of gas.

    I've assumed a 5 MPG difference. My lifetime FE on the Toyos (60K) was 50 MPG. Let's say the Michelin Primacy MXM4s run at 45 MPG for 60K. If so, then the big unknown variable of gas price will determine all.

    There is a breakeven for me, where the Primacys start to cost less than the Toyos, but it would require the average price of gasoline to be $1.63/gallon across the next 55,000 miles. I don't find that to be too believable. At your suggested rate of $3.80 (I paid less than that last night for the first time in many months!), the Michelins will end up costing me $264 more than the Toyos. At the more believable (to me) rate of $4.50, the Michelins will cost me $350 more. That comes to less than a penny each mile or, in my case, about $9.55 per month.

    Would I pay ten buck per month for the safety, quiet and handling differences? I think so.

    One interesting note: If the FE of the Primacys improves, then the cost difference, obviously, lessens. It isn't exactly a linear curve, but the difference lessens by about $115 per 1 MPG increase in FE of the Michelins (above 45 MPG). This means the cost difference drops to about $0 when the Michelins average a lifetime FE of 48 MPG (two less than the Toyos).

    Now, if I put the same Michelins on a BMW . . .
     
    #168 a priori, Oct 21, 2012
  9. F8L

    F8L Protecting Habitat & AG Lands

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    I used TireRack.com pricing and 55mpg vs. 50mpg.

    Toyos = $816 before tax now rebate

    MXM4 = $650 before tax after rebate

    Interestingly, the prices changed since I posted. LOL
     
    #169 F8L, Oct 21, 2012
  10. a priori

    a priori Canonus Curiosus

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    Hmm. So the Toyos cost even more than I'd figured. I'm $16 dollars closer to break-even!!

    Also, I don't live in a climate where I can keep the high FE the year around, so your MPGs are just a bit too optimistic for me. Perhaps in a different model and a different climate . . .
     
    #170 a priori, Oct 21, 2012
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  11. F8L

    F8L Protecting Habitat & AG Lands

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    Ok, so the tires are broken in and the don't feel so squishy anymore. They feel just about as tight as the MXM4 on bumps but they have terrible steering response and feel like they are folding over in hard cornering. This was noticeable before the TRD springs went on any it is even more prominent now. It's funny how much a tire can change after it is broken in.

    I'm still happy with them but unless mpg picks up I will continue to suggest the MXM4 as an all around better choice unless you want the look of the taller tire. :)
     
    #171 F8L, Oct 23, 2012
  12. a priori

    a priori Canonus Curiosus

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    I'm hoping you'll get the MPG pick-up. Of course, I'm hoping for that myself.

    I love everything about the MXM4s -- except for fuel economy. I'm hoping for the pick-up on that end some time soon.
     
    #172 a priori, Oct 23, 2012
  13. F8L

    F8L Protecting Habitat & AG Lands

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    Here are a couple of pics with the springs settled. I used a standard size business card (2"x3.5") because I don't have a tape measure handy. :)

    Front (approx. 3/4" gap from top of tread to top of wheel well)

    IMG_20121024_122054.jpg

    Rear. The top of the tread is basically at the top of the wheel well. It's hard to see because the EP422 has a seriously rounded tread shoulder.
    IMG_20121024_122209.jpg
     
    #173 F8L, Oct 24, 2012
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  14. rjpalaypay

    rjpalaypay Junior Member

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    Am going to do CT200h wheels on my 2012 Prius also. Am I OK with the lug nuts that came with my 15" wheels? or do I need Lexus lugs?
     
    #174 rjpalaypay, Oct 26, 2012
  15. F8L

    F8L Protecting Habitat & AG Lands

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    Yes. That is what I am using.

    The CT lug nuts are keyed so you have to use the wheel lock key. I prefer to not use locks. :)

    Discount Tire/Americas Tire is running their $100 rebate on the purchase of 4 new tires! Couple this with the $70 Michelin rebate or the $80 Goodyear rebate and you'll save big!

    They honored the $100 rebate for the EP422s I bought a week ago! I'm so stoked!
     
    #175 F8L, Oct 26, 2012
  16. F8L

    F8L Protecting Habitat & AG Lands

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    In way of an update, I aired up the new tires to 45/44psi and the ride is a bit harsher when cold outside but isn't bad when temps are in the 70s+. I also noticed that with the higher pressure, my speedometer and GPS readings are "dead on" or as accurate as possible with no decimal showing on the speedo.

    The drawback to this is I will now be driving 1.5-2mph faster than I used to unless I decide to set the CC for 63mph instead of 65mph or 58 instead of 60. Blah
     
    #176 F8L, Oct 30, 2012
  17. SuperchargedMR2

    SuperchargedMR2 Diehard Rams Fan

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    So what have your tanks been getting with the 17" wheels & tires? Did you start a different Fuelly or are you going to just keep the current one running?
     
    #177 SuperchargedMR2, Nov 1, 2012
  18. The Critic

    The Critic Resident Critic

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    He hasn't had the car aligned so his mpg is probably like 40 on a downhill road with a tailwind. LOL!
     
    #178 The Critic, Nov 1, 2012
  19. F8L

    F8L Protecting Habitat & AG Lands

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    I had my first real fill up yesterday. The dash read 52.7mpg I think. The problem I am working through is the difference in the odometer reading. I think that the odometer is reading slow because the new tires do not flex as much while rolling which is why the speedo and GPS agree now. Using an odometer app I saw a minor difference in odometer vs. GPS totals which would come out to a 1mpg difference over the course of a tank. It would also help explain why the car mpg and the hand calculated mpg difference was over 8%. I need to work through this so I know exactly what is going on.

    I'll use my old 17" tire Fuelly. :)
     
    #179 F8L, Nov 1, 2012
  20. SuperchargedMR2

    SuperchargedMR2 Diehard Rams Fan

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    You need to show both of your Fuelly stats in your sig. ;)
     
    #180 SuperchargedMR2, Nov 3, 2012
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