Tire Upgrade

Discussion in 'Gen 2 Prius Accessories & Modifications' started by nyprius, Jun 26, 2006.

  1. mdewberry

    mdewberry New Member

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    Interesting.. Did you go with the standard 185/65/R15 or did you move to the 195? I will check the pressure that they added - so making sure the front tires and back are the same will help with the extreme responsiveness?
     
  2. macmaster05

    macmaster05 Senor Member

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    Lol, you're confusing sidewall ratio and tire width. In the example above, 195 is "smaller" (by your definition less diameter) than 185 because and only because the sidewall ratio is smaller.

    And yes, most cars speedometers read 2mph higher (usually about ~7.5% off), to make people think they're going faster than they actually are. My friend shadowed a CHP officer in college. Google it if you don't believe me. You having to use 205s to acheive a more accurate speedo reading is proof itself.
     
  3. diverlee

    diverlee New Member

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    FYI. Update to below. The suggested replacement tire size is simply an option for added safety margin. It is not required.

    With my recent experience, and I'm very determined, Michelin and many discount tire sellers have balked at selling a 195/60R15 tire for a car with a manufacturer recommended size of 185/65R15. Most have protested such a replacement size will, or may, invalidate either the manufacturer's warranty, or their own warranty. Discount tire sellers are particularly finicky. Buyer beware. If you encounter this problem, you may have limited options.

    Any dealer other than your original tire seller may void your warranty for using a replacement tire size larger than originally recommended for the car by the manufacturer. Buyer beware.

    Make sure you fully trust the original seller to still be in business and honor the warranty in the unlikely event a warranty need arises. Buyer beware.

    A knowledgeable and reputable tire dealer may protest initially. A true tire professional will know the desired replacement size is not remotely a problem.

    Personally, I have enough faith in this tire recommendation, (from this and many sites) and also in my choice of individual tire seller, that the risk is minimal. Still..., you should inquire before placing a final order.

    Further, such a true professional tire seller may balk at meeting a low club/discount price. I did have to jump through hoops to get my preferred and trusted tire seller to match the club prices!

    In the end my research and perseverance was rewarded at an out the door installed and balanced price of $125+ tax, including free balancing, free rotation and free valve stem replacement for life.

    With a 6 year, 90,000 mile warranty, I suspect I'll sell the car long before I need to replace the tires! As they say, your mileage may vary.



     
  4. diverlee

    diverlee New Member

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    Ahhh? The 195/60s at 24.21"? Note that I have not taken the time to confirm your finding. Source(s)?
     
  5. diverlee

    diverlee New Member

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    And? Please share more. Why/how do you consider the tire too responsive?

    I'm seriously thinking about this tire as the OEM replacement, as well as the Michelin HydroEdge.

    You have valuable experience to share, especially with a highly rated tire!

    Please share more specifics so that others may learn.

    I've routinely over inflated my OEM Goodyear Integritys without any discernible difference in handling. Maybe I've missed something.

    Jeez, now you've got me worried.

    I'd be more appreciative of your subjective evaluation of comfort and handling than someones supposedly objective yet unsubstantiated opinion of fact.

    Please? Thanks in advance.
     
  6. talonts

    talonts VFAQman

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    I'm confusing nothing. I understand more about tires that you probably ever will.

    The 195/60-15 is smaller than the 185/65 or 205/60 in diameter, the one parameter that affects odo/speedo, which is what I was discussing. Work on your reading comprehension, and Google something called "context" before swallowing your foot.

    I don't care what "most cars" do. That doesn't mean it's a law, or even correct. I want as accurate a speedo as possible, and have even gone to the expense of custom speedos in the past to get them more accurate.

    And work on your math too. 2mph off and 7.5%? I highly doubt that the OEMs calibrate to 27mph.
     
  7. talonts

    talonts VFAQman

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    No source, just simple math using tire parameters. Note that each tire manufacturer's tire in each size (or even model) won't really match that final diameter (185/65-15 Brand X RoadBlazer2000s may not be the same diameter as 185/65-15 Brand X RoadScorcher3000s ), the only way to be sure of the true size is to measure the circumference. The nicer tire manufacturers will note the revs/mi and that's what you really need to use for the best comparison (if you look at various brand/model 185/65-15s, the revs/mi are all over the map. The Michelin HydroEdge is closest to the OE Integrity, 856 vs 855).
     
  8. talonts

    talonts VFAQman

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    Yes, because a true tire professional will realize that the 195/60-15 and 205/60-15s are within ) 0.26" or less diamter variance from the 185/65-15s. Standard tire depths are usually 11/32" on the better models, and treadwear indicators are at 2/32", leaving 9/32" of tread depth to wear (if you run to the indicators, NOT recommended in most cases (but great for the track)). Multiply by 2 - 9/16" of total tire diameter change new to old. Which is more than double the calculated size differences.

    Some may say the suspension/bearing loading may be different with the wider tread, and yes, that can be true. But enough to be a problem? Exceedingly doubtful. Especially since the tread width touching the ground is usually not "equally wider" than the section width would specify (conversely, it can also be "more wider" (ouch, I know) than expected, as most performance tires have straighter sidewalls, leading to tread widths much closer to section widths as compared to "standard" tires).
     
  9. macmaster05

    macmaster05 Senor Member

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    I was trying to think of a really good comeback but I couldn't so I'll just say this:

    You have F*@&!^#% flames on your car!
     
  10. talonts

    talonts VFAQman

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    Go away, wastoid. They're not on my car, that is a color-shifted version of an official Toyota advertisement.

    You are a complete waste of time and energy, hello killfile.
     
  11. uclabruins

    uclabruins Member

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    I'm planning on getting the Yokohama Touring-S in either 185 65 15 or 195 60 15 since it's less expensive than other options, I live in Los Angeles, and it is low rolling resistance. Hopefully, it's good since it got decent ratings from consumer reports.
     
  12. macmaster05

    macmaster05 Senor Member

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    Cool, dude. Now you can add name-calling to your impressive resume. :rockon:
     
  13. talonts

    talonts VFAQman

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    You can try that, but don't be surprised if it gets more squirrely. The 2Gs are designed for a 2-3psi differential to equalize tire contact patch and handling. Unless you have a lot of added weight in the rear, running equal pressures F/R tends to make the car twitchier.

    If I were you, I'd try going up in pressure. The higher the pressure, the firmer the sidewall, the less twitchy it will be (which is why Integrities will never be as stable as decent aftermarket tires, the sidewalls are the thinnest/floppiest I've run into). The only real drawbacks to higher pressures are the affect on your butt, and slightly increased chance of hydroplaning. Neither of which is great enough IMO to avoid increasing the pressures. Most in the know tend to run at or very near the sidewall pressures (taking into account the built-in 2G Prius 2-3psi differential), not the doorjamb pressures, which are set for driver comfort, not tire safety (witness the Ford/Firestone debacle).

    I run 44/42 on the HEs on my car at all times. The stability is so much better than 35/33.
     
  14. jeep2prius

    jeep2prius Reformed Jeepster

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    I'm also looking to replace my tires and strongly considering the 195/60/15 upgrade and the Yoko Avid Touring-S (currently on sale at my local America Tire). Since I'm just down the road from you in Long Beach and driving in the same traffic/weather, let me know what you think about Yoko's when you get them.

     
  15. uclabruins

    uclabruins Member

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    yeah, i'll let you know. i'm not sure which way to go. i kind of want to maximize MPGs, but also was thinking about slightly better handling. i'm not sure how much of a MPG hit i'd take when going with the 195 60 15 tire.
     
  16. talonts

    talonts VFAQman

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    No real way to know without testing. You're more likely to lose/gain mpg with a different make/model tire than the barely larger 195 section width. You could see if anyone has reported mpg change for the 185 size, and the 195 really shouldn't be too much different. Might be the tiniest bit lower than the 185 of the same model.
     
  17. Redsnake

    Redsnake Can drive anywhere

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    OK so I got my new tires installed and boy it looks sexy!!!! I took before and after pictures (just as in the commercials) :D and will post them soon.

    The first thing which I had to do was to make a quick turn over ice and a large sheet of ice next to my home (courtesy melted snow from the days before) presented the perfect opportunity to go crazy. And I did take a fast left turn to go over the sheet of ice and a left again..... the cars skid control beeped and lights blinked but the tires picked traction very quickly as soon as it got some footing which was kewl. Loved it.

    Didn'tdo much driving but checked my Garmin GPS speedometer to my car's to see where I was at. Remember, before, with my balding GY Integritys in front, it was spot on. Now I see anywhere between 1-2 mph difference with the car showing a higher mph. This is on a variable speed with max speed less than 50mph. I will test this on a highway with constant speed slabs and post the results soon. I have my tire pressure at 38 psi cold on both F/R. I am not too happy with that setting. Any recommendations? I was told that HE has a max 40psi on its wall.

    We are expecting good snow tonight and all through Sunday. Cant wait to test it on snow.

    Cheers.
     
  18. talonts

    talonts VFAQman

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    DO NOT run the same pressure F/R on 2G Prius, it is not designed for it, you will have a much twitchier ride, use 2-3psi lower in the rear. HEs have 44psi max sidewall, so you can easily run 44/42.
     
  19. Redsnake

    Redsnake Can drive anywhere

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    You are right.... I checked it myself yesterday and it was indeed 44... I asked the tire guy when he was installing it to put the pressure at 42/40 cold but he looked at the sidewall and said max is 40. I was surprised but didnt bother checking it myself (lazy me). I will bump it up.

    I took my car out in snow yesterday and it was fun. Yes its not perfect but then you cant expect an all season tire to have perfect traction in lots of snow but it was good. I did not have much problem taking turns and maintaining lanes. The tires gripped well.

    Today while going to office I did have an incident though. I had to stop for signal on an up incline and when it was time for me to move, I was stuck.... didnt look like the wheels were responding though I might be wrong. The anti skid thing was doing its show. So I took the car in reverse a bit and D and after a few attempts got response from the wheels to move ahead. Did not have a problem while the car is in motion. I have heard of this in some posts. Is there a solution to oversome this. Its kinda embarrassing to have such an advanced car stuck in snow.
     
  20. uclabruins

    uclabruins Member

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    A priuschat member in San Francisco said the Touring-S got approximately the same mileage as the Integrity (stock 185 65 15 size).
     
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