Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Can someone help me identify these tyres/size

Discussion in 'Riding Gear and Bike Accessories/Parts' started by burner, Aug 22, 2015.

  1. #1 burner, Aug 22, 2015
    Last edited: Aug 22, 2015
    Hi Guys,

    I'm working on a cafe racer project (SR400) and wanted to run larger/sportbike tyres. I keep seeing the tyres on the below bike pop up and I'd love to find a way 1) find out what they are/size and 2) fit them to the SR.

    Does anyone happen to know what make/model they are or want to take a crack at the size?


    The above appears to be a CB, however I've seen them on an SR as well...


    It looks like I'll also need to upgrade the rims to accommodate the larger size. I don't know a ton about tyres so I wouldn't really know where to start with the exclusion if taking the images into a bike tyre store which I might do over the weekend.

    Another question I had was how the larger tyres may or may not effect performance and/or safety?

    Thanks for your help.
  2. The tyres on the white SR are Michelin, not sure of the tread pattern.
    When looking at tyre sizes you ideally need the same rolling radius as the original tyres.
    To get this you need to understand the make up of a tyre size.
    The figures for tyre sizes nowadays are made up of metric, imperial and percentages.
    Take the tyre size 110/80-16,the end figure 16 is the size of the rim in inches, the 110 part is the width of the tread in millimetres, and the 80 is the height of the sidewall (the profile), this is a percentage of the width of the tyre tread, so in this case 80% of 110 is 88 so the height of the sidewall is 88mm.

    All standard tyres use a 80 series profile, when you use a smaller percentage you get a smaller sidewall, which is where the term "low profile tyres" is used.

    On older tyres where the size is something like 4.10 x 16, this is all imperial being a 16 inch rim size and the measurement across the tread is 4.1 inches, the height of the sidewall will still be 80% of the tread width.

    To convert this size to a similar metric size you would convert 4.1 inches to mm which is 104mm. As tyre tread widths only go in tens of mm you could either use a 100mm width or a 110mm.
    On this example we'll use the 110, add the percentage for a standard tyre profile and you'll get a 110/80, then add the rim size and you end up with a 110/80-16 which would be the closes thing to a 4.10x16.

    To get the same rolling radius as the standard tyre you need to go up two sizes on the tread width and down one size on the sidewall profile.
    Take the 110/80-16, up two sizes on the width would take it to a 130 and then down one size on the profile which would be a 70 series.
    You end up with a 130/70-16, this size tyre will have the same outside diameter as the 110/80-16 but will have a wider tread.

    Clear as mud eho_O

    If you managed to read this far and you're still awake, well done :sleep:
    • Informative Informative x 2
  3. zooming in, looks like 180/70 17? maybe 190?

    • Funny Funny x 1
  4. Definitely not a 180, or 170. I'd say closer to a 130?
    And the first pic is an IRC Road Winner RX-1.

    My Mk1 eyeball may be out of calibration, so take that with a grain of salt!
    • Winner Winner x 1
    • Like Like x 1
  5. Thanks a ton for all this info guys - really good to know valk, cheers for taking the time to post that.

    I am assuming I'll need to upgrade the rear rim to fit the tyre? Any idea what size I should be looking for? I can always take it down to balmain motorcycles and get them to diagnose it.
  6. Legend mate thank you!
    • Like Like x 1
  7. Welcome bud.

    I think standard rim width is 4 inch? In which case, yes, you'll need a wider rim to fit the 130. (5 inch)