pros and cons of 20" vs 19" vs 18" - Page 2
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Thread: pros and cons of 20" vs 19" vs 18"

  1. #21
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    pros and cons of 20" vs 19" vs 18"

    Quote Originally Posted by Augie View Post
    How does the wheel height change the stiffest of the tire sidewall ? It doesn't. The ratio of the tire does. a 35 or 40 sidewall on a 18, 19, 20 or 21 is the same stiffest.
    .
    You are exactly right. However to maintain identical tire diameter, increasing the wheel diameter means changing the tires ratio to a lower profile, thus increasing the stiffness as you said.

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    Re: pros and cons of 20" vs 19" vs 18"

    Except for the top it's like looking in a mirror
    Augie

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    Re: pros and cons of 20" vs 19" vs 18"

    I've got another question. My 2014 Cayman S came with 20" wheels and OEM Pirelli tires. When pulling out of the dealer's parking lot the front end had a "bumping" sound at low speed with a hard angle turn. Similar to pulling out of your driveway to get into the road. I was told by the dealer that the bump or clunk was normal and nothing to be concerned about. Once the car is up to speed the front end noise disappears. However, I took my car into a tire dealership to order some new tires and the serviceman told me that this front end noise was odd and that I should get it checked out. Anyone else know what I'm talking about?

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    Re: pros and cons of 20" vs 19" vs 18"

    Quote Originally Posted by blross View Post
    I've got another question. My 2014 Cayman S came with 20" wheels and OEM Pirelli tires. When pulling out of the dealer's parking lot the front end had a "bumping" sound at low speed with a hard angle turn. Similar to pulling out of your driveway to get into the road. I was told by the dealer that the bump or clunk was normal and nothing to be concerned about. Once the car is up to speed the front end noise disappears. However, I took my car into a tire dealership to order some new tires and the serviceman told me that this front end noise was odd and that I should get it checked out. Anyone else know what I'm talking about?
    Look up Ackermann effect. It's been discussed many, many times on P9.
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    Re: pros and cons of 20" vs 19" vs 18"

    Quote Originally Posted by cajundaddy View Post
    19" and 20" wheels are all about the look with zero performance advantage. 18" are the choice for all GT3 Cup and GT4 Clubsport race cars and tire availability is a lot better with 18s. That said, if you like your 20" you can keep your 20".

    https://www.yokohamatire.com/motorsp...-cup-challenge

    https://www.porsche.com/internationa...turesandspecs/
    Hi,

    If I go with 18" for track and would like to go with something like RE71R, what tire sizes would you recommend? It only has 245/40/18, 245/45/18, 255/35/18, 255/40/18 and rear 265/35/18, 265/45/18, 275/35/18 and 285/30/18...

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    Re: pros and cons of 20" vs 19" vs 18"

    Steve,
    Thanks for the reference to the Ackermann effect. I hadn't heard of it before. Wikipedia explains it well and then adds:
    Some racing cars use reverse Ackermann geometry to compensate for the large difference in slip angle between the inner and outer front tyres while cornering at high speed. The use of such geometry helps reduce tyre temperatures during high-speed cornering but compromises performance in low-speed maneuvers.
    I don't know if modern Porsches have reverse Ackermann but it would further explain the pronounced tire skipping mentioned.
    Bern
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    Re: pros and cons of 20" vs 19" vs 18"

    Quote Originally Posted by acexxon View Post
    Hi,

    If I go with 18" for track and would like to go with something like RE71R, what tire sizes would you recommend? It only has 245/40/18, 245/45/18, 255/35/18, 255/40/18 and rear 265/35/18, 265/45/18, 275/35/18 and 285/30/18...
    I'm interested in hearing more about this too. I'd like to run 18's for auto-x on my 2014 Cayman S. It sits on 19s now with the standard 235/265 40 rubber. I was thinking of mounting RE71s in 235/265 45 on the 18s to keep the overall diameters between the two sets w/in .1 inch.
    I know that the 2014 owners manual only allows for 18" winter tiresicon on the Cayman S. It also recommends the 235/265 in a 45 profile for those winter tires. It only recommends 19 and 20 inch tires for summer performance set ups.
    Love to hear thoughts on performance and handling issues going from 40 to 45 profile on a high performance tire. My thoughts: negligible.

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    Re: pros and cons of 20" vs 19" vs 18"

    I'm not sure what Bridgestone has available but I run Nitto NT-01 in 235/40-18 and 275/40-18 for DE. They fit and wear without any complications. These have a smaller diameter than stock and lower the car a bit but I"m happy for that at the track.
    Bern
    2016 Cayman S
    Track at Thunderhill, Laguna Seca, Buttonwillow

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    Re: pros and cons of 20" vs 19" vs 18"

    Quote Originally Posted by bernb6 View Post
    I'm not sure what Bridgestone has available but I run Nitto NT-01 in 235/40-18 and 275/40-18 for DE. They fit and wear without any complications. These have a smaller diameter than stock and lower the car a bit but I"m happy for that at the track.
    Bern
    Thanks for your input. Can you tell me the specs on your wheels (width and ET)? Thanks!

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