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Replacing Tires

gusgus Posts: 254
A continuation of Welcome Conference Topic #323.
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  • pomanpoman Posts: 46
    OK, no one posts here. So I'll be the first woohoo. Anyway, in case anyone sees this message, help me out. I upgraded my tires from 205/60r16 to 215/45ZR17 on my Solara. The old cold tire pressure is 32psi. What should I put for the new tires? The same psi or higher??
  • guitarzanguitarzan Posts: 632
    Boy, that is a great question. I would call the manufacturer and see if they have a recommendation. After all, the tire pressure should be set to match the characteristics of the car. If they don't have a recommendation, that being an extremely aggressive tire for that car and all, I would contact a Toyota enthusiast group. Probably only someone who has made a similar switch will have recommendations on what works best. I'm really curious, why the switch to those tires?
  • pomanpoman Posts: 46
    Lower profile tires are more stable, lower sidewall has a better grip to the road. Plus is wider, and a new look on the wheel. According to the sticker beside the door frame, the original 195/65r15 has the tire pressure of 29psi. The next upgrade is 205/60r16, which I replaced had the pressure of 32psi. So now I have the 215/45ZR17 so I set it at 35psi. Don't know if that's too much or not. The guy at the tire store told me to set it between 35-40psi depends on how you feel about the ride. The max pressure the tire can handle is at 44psi. So just want other ppl's opinions.

    Hey I didn't know you own a Acura CL, guitarzan. I was going to get that but it's just a bit slow and pricy. I was going to get the Accord coupe EXV6 but they were out of stock. So i bought the Solara instead. I love it very much. How's the CL doing??
  • pomanpoman Posts: 46
    Doh, I meant small and pricy guitarzan, your car is actually a bit faster than mine until I got my supercharger from TRD in June, then I can hall [non-permissible content removed]!:) Did u get the 2.2 or the 3.0CL??
  • guitarzanguitarzan Posts: 632
    The Cl is doing very poorly :( Yesterday I noticed a few cracks in the front spoiler. I'm pretty sure they were gotten by nailing some chunks of ice in the road during our severe weather.

    I knew there was more to this story! Supercharger, eh? That would be GREAT for the CL. I got the 2.3, because I refuse to drive an auto :)

    What did the charger cost? (I figure a similar one might work on my car.)
  • pomanpoman Posts: 46
    The supercharger from TRD (Toyota Racing Development) is going to be about $2995. 5 years/60,000miles warranty if installed by the Toyota dealer. Don't think it would work on yours. It's for V6 3.0 Toyota engine only :( YOu could probably get one from the aftermarket.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,420
    Re: previous posts on inflation....nope, you don't go by what it says on the tire itself! that's way too much air! You're already running a little more risk with low profiles on possible road hazard damage, and making them too hard wouldn't help that situation, seems to me.

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  • bjmeyerbjmeyer Posts: 24
    Oh, would that there were a simple answer to this question. The tire pressure manufacturers recommend is a compromise between ride, handling and braking, speed capability, and tread life. Lower pressure (within a certain range) will give a softer ride, but generally poorer handling and braking. Also, a softer tire flexes more, so gets hotter, which increases wear and affects safety at high speed. Also, given the very low profile of your new tires, too low a tire pressure could be asking for rim damage if you hit a pothole or such. You don't want those sidewalls to flex too much.

    Higher pressure gives a harder ride, generally better handling and braking, and less flex, so less heat buildup.

    TOO high or low, of course, will drastically affect tread life because only a part of the tire will contact the road fully. Too high a pressure will cause rapid wear in the center, too low a pressure will wear out the edges.

    Racers use something called a tire pyrometer. It measures tread temperature. You take readings across the width of the tread, and adjust tire pressures so that temperatures are even across the tire. (This is a basic rule--there are exceptions, of course).

    I'd guess that as long as you don't go below 32psi you're probably ok. If you don't mind the stiffer ride, 34-35 will probably give you a little better handling and braking. Since you probably don't have access to a pyrometer, get a tread depth gauge, and monitor tread wear at the center and edges. If the tire seems to be wearing faster in one place, adjust pressures accordingly.

    HTH,

    Bob
  • guitarzanguitarzan Posts: 632
    Bob, I'm only guessing that a daily driver has a consistent temperature across the tread (at a given pressure), because the force exerted across it is pretty much the same. Is this wrong?
  • pomanpoman Posts: 46
    Thanks for responding Bob and Mr_shiftright. That's a great info there. Apparently I have it set at 39psi now and the car has lesser vibration than before (35psi, plus multiple balances on tires.) Hopefully it would be okay. I have them balanced the tires for the third times this week becuz of that light vibration from the steering wheel,break and gas pedal. Everytime I went back there the wheel was unbalanced again. Don't know why. Kinda pain in the [non-permissible content removed] now for all this wheel change scenario...
  • mt1mt1 Posts: 4
    I have tires on my car that are 175/65 r14. How is that different from say 205/70 r14 or r15?
    Thanks in advance.
  • guitarzanguitarzan Posts: 632
    The 175 is the width of the tread, in mm I believe. The second number, 65, means the sidewall height is 65% of the tread width. The r14 means a radius of 14", or that it fits on a size 14 wheel.
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,420
    the tires could be defective...unusual but it happens...they aren't quite round and no amount of balancing is going to fix them...if all else fails, you can have that checked.

    MODERATOR

  • No, depending on the tire pressure the temperature can vary quite a bit across the tread. The catch is you have to measure imediately after completing a drive under the conditions being tested, or the temperature will even out.

    Temp varies for the same reason over or underinlating a tire affects the wear pattern. If the tire pressure is too low, the center of the tread actually "collapses" to a degree while driving, so that part of the tread makes little contact with the road. Over time, you see this as rapid wear of the outside edges of the tread compared to the center.

    If the pressure is too high, the reverse happens. The center of the tread actually "bulges," so the edges of the tread aren't in good contact with the road. Over time you see this as excessive wear i the center of the tread.

    It's true that on a street tire, minor changes in pressure probably won't have much effect on tread temperature, but it will occur. It may also be true that steel belted radials will be less affected by overpressure than other types, but I don't know that for a fact.

    One interesting aside: There are now remote, infrared sensing tire pyrometers that can be mounted in the fender wells of a car to measure tread temperature in real time, while the car is being driven. I don't know if they are sensitive enough to detect differences across the tread, or only average temperature. I am, however, certain that they are very expensive.
  • guitarzan:

    Is the width measurement the width of the tread, or the section width. That is, the width at the widest part of the tire? Probably not a significant difference, in either case.
  • Thanks BJ for the interesting info.

    I'm sorry about my post, and glad you corrected me. The first number on the tire is the section width like BJ said.
  • Ah, should have done this quick search before to give the whole truth in a nice format:

    http://www.tires.com/discount_readsidewall.html
  • Mr_ShiftrightMr_Shiftright CaliforniaPosts: 44,420
    Nice link, thanks guitarzan!

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  • KCRamKCRam Mt. Arlington NJPosts: 3,516
    Here's a handy definition list:

    example: P185/75R14

    P - passenger car tire, can also be LT for light truck, T for temporary.

    185 - section width in millimeters. measured from the widest point of an unladen tire (as opposed to the bulge width of a loaded tire)

    75 - aspect ratio - the section height of the tire divided by the section width. Section height is generally recognized as the distance from the bead to the outside point.

    R - radial construction. Can also be B for bias-ply

    14 - whell diameter in inches

    after the diameter, some tires will also show a load rating. P-tires are generally expressed as SL (standard load) or XL (extra load). LT-tires usually have the load rating expressed in a letter; each letter represents in its numeric form 2 tread plies per letter. Example: B is 4 ply, E is 10 ply.

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    Need help navigating? kcram@edmunds.com - or send a private message by clicking on my name.
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  • Recently, I purchased a 92 Q45 with new Viper Tires. Well, they have separation ie defective. I had them spun and aligned and found that the tires are out of round and I have a very bad vibration that is getting worse. I am trying to locate who sells these tires or possibly contact the manufacturer. Any information will help. Thanks.
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