Tyre Size Calculator V2: Wishlist

I’m currently working on version 2 of the Tyre Size Calculator, it’ll fix some inconsistencies in the current version and add a few new features that commentors have asked for e.g.

  • Bike Tyres
  • Mud Tyres

I’m also thinking of adding the option to specify the wheel width so you can see how fat or stretched the selected tyre size will be on a given wheel width.

If anybody has any comments of suggestions then feel free to post them below πŸ™‚

53 thoughts on “Tyre Size Calculator V2: Wishlist”

  1. For those of us wanting to size a suitable space saver wheel, it would be good to have the calculator work down to the 115 and possibly below width ranges.

  2. It would be nice to have revolutions per mile/km, speed difference (obviously only if speedo is correct) Maybe even RPM at given speed


    1. Reduction or increase in engine revolutions at a given speed.

      For example, the reduction in Engine revolutions by fitting 275/75 from original 265/70 at a steady indicated 120 kph


  3. Hi Insomniac. I’ve been trying to find a tyre size calculator that includes rim-width in it’s inputs – this can have a considerable effect on sidewall height, i.e. a 205/45 tyre on a 8″ rim will be seriously stretched, but will be baloon-like on a 6″ rim.
    If you can work out how to incorporate this (preferably along with a cross-sectional view) I can guarantee you’ll get loads of hits just from the euro-look brigade, let alone the ricers, pro-tourers etc πŸ™‚

  4. Here’s a couple of things to add:

    – High Flotation Tires
    – Tire Width to Rim Width ratio with a “Acceptable”/”Warning” note
    – What is the IDEAL tire to rim width?
    – Rim offset calculator (to allow you to go from one width to another while minimizing the risk of damage to the wheel bearings)

    Too narrow of a section width to rim width ratio becomes VERY dangerous due to the fact that the tire bead can come free of the rim easier. In addition, it can also cause the outer sections to press against the road and the center to lift up creating an unusual treadwear pattern. However, I know you can usually get away with wider tires than rims. But, how wide is too wide? I’ve seen people run very wide tires for their rims and not have problems. But, I also have seen some tires that just wear funny because of how they’re made. Too wide of a tire causes the tread pattern to baloon out causing uneven treadwear and certain handling issues.

    Currently, I run P255/70R15 on my 15x7J factory rims. According to research I’ve done, the manufacturer provided multiple sizes for my Jeep. They were 215/75R15, 225/70R16, 225/75R15, 235/75R15, and 245/70R15. My door tag says 225/70R15 mounted on 15x7J rims.

    Interesting. isn’t it?


  5. – metric / imperial sizes both shown. (ie so we know as 235/85 16 is nearly 32″)
    – switchale end view (to show comparative width).
    – over/under speeds shown in imperial and metric.

  6. 1)Please stay with metric units – it’s great and so much easier.
    2)Be uniform in the units when giving the charateristic dimensions of a wheel – i.e. use either cm or mm for the Total Diameter and the Rolling Radius and the tyre width etc. I prefer mm to cm here.
    3)Please use the correct abreviation – km not KM (not that I noticed this mistake in the 1st version – just pre-empting).
    4)For me there are 2 components – a rim and a tyre. When you assemble the two components you have a wheel! (Perhaps I’m the only one in North America who thinks this way.)
    5)Perhaps I didn’t look carefully enough at the 1st version – but showing the meaning of the terms diagramatically would be nice. For instance, exactly what is meant by “Rolling Radius”?
    6)Thank you for your great calculator.

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