Home Forums General Karting Discussion Rim Width

This topic contains 7 replies, has 5 voices, and was last updated by  Joshua Guiher 3 years, 9 months ago.

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  • #22270

    Joshua Guiher
    Participant

    I am new to karting this year and need to get a couple sets of wheels. I have a Birel S3, so Freeline and Douglas seem to be my best options.

    A new set of Douglas wheels is about the same price as used Freeline it seems.

    For Freeline, they only seem to come in 130 / 210 for a set, while I have seen the Douglas come in 212, 214, 216 & 218 for the rears.

    How do you know which size you want? I understand that a 212 would have less contact area, making the rear slide faster, but it would also have a bigger circumference so you would need less revolutions on the rear axle to get down the straight.

    Where should I start?

    #22271

    David McDowell
    Participant

    Josh,

     

    You are looking at rim width not circumference. Most rear wheels ran today are 5″ circumference.

    #22272

    Joshua Guiher
    Participant

    Yes, but as you stretch the width from 210 to 218, does that now change the circumference (roll out), at least a small amount?

    #22277

    Walt Gifford
    Participant

    You want wheels that are 1″ wider than your tires. Don’t worry about the roll out, RPM is controlled by changing the rear sprocket.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

    #22278

    James McMahon
    Participant

    Welcome to karting.

    Keep in mind, assuming tire pressure remains the same, tire/wheel width actually has no affect on contact patch size, only shape. If you significantly change the circumference then that’s different, but otherwise, the adage that a wider wheel = bigger contact patch is incorrect.

    What class are you running?

    #22283

    Joshua Guiher
    Participant

    Yamaha Senior (Piston Port) following WKA rules

    #22287

    Gary Lawson
    Participant

    As mentioned contact patch is unaltered and circumference differences are cancelled out by gear changes. The difference is the change in sidewall stiffness. Wider wheels stiffen the sidewall and decrease grip. On a spec tire like ylc you want the 210 or 212. No bigger.

    #22289

    Joshua Guiher
    Participant

    Thank you all for the responses, I understand now.

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