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Aug09 GP MJD 1,35,000km completed

Discussion in 'Punto 1.3 MJD' started by Pran, Oct 25, 2010.

  1. Pran

    Pran Superiore

    Messages:
    748
    Bangalore
    Grande Punto 1.3
    @gurjinder : Agreed. Even my Siena had 100PCD on it and it did not wobble. Since I have the regular drive to my native I prefer to be on the safer side.

    Okkayyy guys, I am getting my wheels balanced this weekend, taking TFI members advice :)
    Last edited: Jun 10, 2011
  2. jayakrishnakola

    jayakrishnakola Regolare

    Messages:
    439
    Bangalore
    nice review pran!!!

    have u got the balancing done ?
    how is ur ride now?
  3. Pran

    Pran Superiore

    Messages:
    748
    Bangalore
    Grande Punto 1.3
    Thanks Jayakrishna.
    I am yet to do the balancing, waiting for the spigot rings to arrive so that I can get everything done in one go.

    Ride is a bit on the harder side even after maintaining a tyre pressure of 28psi, I might have to try 26 now, the tyre shows no sign of low pressure even at 28.

    The rear mudflaps are touching the tyres, so I am planing to remove it, it always used to curve inwards, it is usually the other way I have seen on most cars.
  4. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Pran, 26 might be going too low. The tire may not show signs of low pressure due to its strong and rigid construction , but low pressures will definitely affect it in the long run . Air in the tyre also helps the tire maintain its correct working 'posture', if i can use that word. :p

    Gurjinder.
    Last edited: Jun 13, 2011
  5. Cinju

    Cinju Esperto

    Messages:
    1,333
    Trivandrum
    Guru ... when we are upgrading our tyres to a different one than the stock, how do you calculate what exactly is the tyre pressure required ? I think it may differ from the stock pressure right. Normal ranges are between 28-34. But how do we know the optimum ?
  6. Pran

    Pran Superiore

    Messages:
    748
    Bangalore
    Grande Punto 1.3
    Yes Gurjinder, I agree with you. If there is someone here using CPC2 I would like to hear from them too. Anyways my idea of "higher profile gives better comfort" is being proved wrong. So far the grip seems fine for city driving, yet to do some long trips to really test the limits and try and trigger the ABS.
  7. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Like Pran, you gotta set it at the levels you find the best, avoiding extremes of low and high pressures.

    Visual inspection is also a good way. After a run on a nice road you'll be able to tell whether the tire pressure you're running enables the tire to have a nice and even contact patch or not.

    Plus, the feel you get sitting in the car while driving/going through bumps etc tells a lot about the tire pressures you should run.

    Gurjinder.
    P.S This is just an amateur's way to gauge tire pressures. Royj's input would be appreciated here,
  8. royj

    royj Esperto

    Messages:
    1,306
    Trivandrum
    Thanks Gurjinder, but my guess is as good as yours in this case. I am no expert when it comes to tire pressure. Personally I would prefer to err on the higher side, and I would not go below 30psi.

    However if we try to analyze mathematically, we could try working out as follows -
    Get the contact patch area for four tires. The weight of the car is supported over this contact area. This force is balanced by the air pressure in the tire.
    Now when we have a tire of different size, get the new contact patch area and the new air pressure required will be proportional to the contact patch area of the original tire. So a wider tire could mean a reduced pressure, but change in side wall height alone will not have an effect.

    Also the contact patch area changes with the air pressure - so another approach could be to change the pressure so that contact patch area remains same.

    I am not sure if this is the right approach, it is just off the top of my head.. :p

    Hey isn't these two contradictory?
    Last edited: Jun 13, 2011
  9. Pran

    Pran Superiore

    Messages:
    748
    Bangalore
    Grande Punto 1.3
    Roy, what I meant is when I upgraded from 175 70R14 to 195 65R15 the sidewall height increased from 122.42 mm to 126.74 mm. This means more cushion from the increased rubber on the sides. This theory of mine turned out to be false.

    My comparison is wrt the stock B250 on the same roads to my office and back. Current configuration initially at 30psi and now at 28psi is not as comfortable as the old stock tyres with 30psi in front and 28psi in rear, I remember trying 34psi on the old tyres and did not see any drastic change on the comfort side.

    Any by the way any idea how these international shipping work?. The order for spigot rings from http://www.hubcentric-rings.com was my first international order online and I am not sure how the customs duty will be taken care.
    Last edited: Jun 13, 2011
  10. royj

    royj Esperto

    Messages:
    1,306
    Trivandrum
    I have experience only with 20North, the items I have ordered reached me in two to three weeks, customs and everything taken care of. Check with Soccerfan, he had ordered from hubcentric rings.

    As for the riding comfort, I guess the CPC has a stiffer sidewall to negate the cushioning effect of the additional 4.32mm.

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