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All about car tyres and wheels

A reference for car owners: sizes and markings, offset and balancing, winter and summer. We sell nothing.

The essentials About the author

Tyre size calculator

195/65 R15 → 205/55 R16
Standard tyre size

Reads as 195/65 R15

The size on the fuel filler flap or the driver’s door pillar.

You want to fit

Reads as 205/55 R16

Everything recalculates automatically.

Ground clearance will change by-1 mm The speedometer shows 100, your true speed is 99.55 km/h. Overall diameter -0.5 %, width +5.1 %.

Within 5%: the geometry is acceptable. Overall diameter -0.5 %, width +5.1 %.Over 5%: the tyre width Wt differs by +5.1 %. Fitting this tyre is not recommended: the load on the suspension, the clutch and the gearbox goes up, and the wheel may foul the bodywork or the suspension.

Geometry, table, speedometer and wheel diagram Tyre size calculator

The essentials

  1. Tyre size calculatorCalculating tyre and wheel geometry, plus the change in ground clearance and true speed when you fit wheels of a different size.
  2. Tyre markingsTyre size, speed rating and load index, season, date of manufacture, direction of rotation, coloured marks and retreads.
  3. Alloy wheels: everything you need to knowCast, forged, steel and replica wheels: how they are made, how they differ and which ones will suit you.
  4. Steering wheel vibration: causes and curesAfter a seasonal tyre change (or wheel change), the steering wheel starts to vibrate at a particular speed. Sound familiar?
  5. All about wheel offset (ET)Motorists often either pay no attention to offset as a parameter, or sometimes deliberately ignore it when choosing wheels.
  6. All about winter tyresIt turns out winter tyres come in more than one kind! They are made for different roads, different climates and different ways of using a…
  7. Wheel balancing: why, how often and whereSadly, many motorists are not especially fussy about which tyre fitter they trust with fitting, balancing and repairing their wheels.
  8. Buying part-worn tyres: step by stepBuying part-worn tyres is mostly a step you are forced into, so there is not much point talking yourself out of it.

SectionsSix topics that hold every article on the site.

All aboutTyresbasics, 22 articles How to chooseTyreschoosing, 25 articles Pressure, storage, seasonCare13 articles How to chooseWheelschoosing, 14 articles All aboutWheelsbasics, 11 articles Fitting and repairService12 articles

From the author

This site was inspired by a lively argument between two experienced motorists on one of the car forums. The argument was about choosing winter tyres, and each of them, naturally, praised his own. There was nothing strange in that, except that the tyres in question were completely different, meant for entirely different conditions, so comparing them, let alone arguing over which tyre was better, made no sense at all.

Sadly, only a chosen few motorists make an informed choice of tyres, even though, given how wildly road surfaces vary in Ukraine, that choice matters a great deal - because tyres are, first of all, safety.

So the decision was made to create a small information site that could answer motorists’ questions about choosing tyres and wheels, storing, using and servicing them correctly, without pushing particular manufacturers or other things that are “profitable” for sellers. I will be very glad if you find the information on this site useful.

This project was created for the benefit of car owners, and it does not aim to sell or push anything. Information, and nothing but information: that is our motto.

With best wishes,
Serhii Maslov, the site’s author