Tyre Size Calculator/Tire Plus Sizing Calculator - Calculates Tyre Dimensions for Plus Sizing

Tyre Size Calculator/Tire Plus Sizing Calculator helps you to find the optimal tyre size when you install the larger wheels on a car. It calculates the tyre dimensions for plus sizing.

The tyre plus sizing or the tyre upsizing is the procedure of replacing a wheel with a larger one and mounting a suitable tyre on that wheel, the tyre with a smaller sidewall height(lower series, aspect ratio) than it's on the original equipment(OE) tyre, while keeping an overall diameter and a circumference of the new tyre approximately the same as they are for the OE tyre(i.e., stock tire).

Plus Sizing - Upsizing

The most popular Plus Sizing methods are:

  • Plus One - utilizes a larger wheel with the one-inch larger diameter than the OE wheel's diameter, in combination with a new tyre which has suitable, smaller tyre sidewall height than the OE tyre's sidewall height, represented by a lower tyre aspect ratio(i.e. tyre series/profile). Also, the new tyre has a larger tyre width(i.e. section width) than the OE tyre's width.
  • Plus Two - utilizes a larger wheel with the two-inch larger diameter than the OE wheel's diameter, in combination with the suitable tyre, the tyre with a lower aspect ratio(AR) and a larger tire width than the OE tyre's AR and width.
  • Plus Three - utilizes a larger wheel with the three-inch larger diameter than the OE wheel's diameter, in combination with the suitable tyre, the tyre with a lower AR and a wider tire width than the OE tyre's AR and width.

All these plus sizing methods require a larger replacement wheel/rim, whose width affects the tyre choice also, besides its diameter.

Tyre Plus Sizing Calculator

In order to get the list of optional(i.e., replacement) tyres, that are adequate for your new wheels, in the plus sizing calculator below, select your original equipment(OE) tyre size, the new wheel/rim diameter size and click on "Show Optional Tyres for the New Wheel" - the orange button.

NEW feature: Or, You can display adequate tyres for all three Plus Sizing methods: Plus One, Two and Three; at the same time, by clicking on the "Show Plus One, Two 'n Three Tyre Sizes" - the blue button.

The calculator lists optional/alternate tyre sizes, based on the entered OE tyre size, where the overall tyre diameter difference between an optional tyre(OT) and the original equipment(OE) tyre fits within the range of -3% to +4% (+5% for Winter tires) of the difference between the OE overall tyre diameter and the OE wheel diameter (OE TD - OE WD or 2 x OE sidewall height).

This formula is used by the leading tyre manufacturers.

Tyre Dimensions

Plus Sizing Calculator

select OE tyre size

eg. 195/65R15

/ R
select new wheel diameter size


NOTICE: Tire dimensions presented in the resulting table, as possible new tire dimensions for the specific new wheel diameter you've entered, aren't all suitable for your car.

The tire dimensions listed satisfy only one criterion in the quest for a new tire dimension, the one that says that the new tire diameter has to be in a certain range in relation to the entered tire size(which should be the OE tyre size) diameter.

Next thing you should do is to find the right wheel for the chosen tire size. You already have one wheel dimension, the wheel diameter, but you also need to know the wheel width. The wheel width has to be suitable for the selected tire size. Every tire size has the measuring rim and the approved rim width range.

For finding the appropriate wheel for the tire size you may use our Wheel/Rim Size Calculator in which you can enter the chosen tire size and you'll be presented with the adequate rim width range for the tire size. The chosen wheel will determine the real tire size when the tire is fitted on the wheel. An assembly consisted of the tire and wheel has to be adequate for your car.

That's ok but it's not enough for the proper tire to rim fitment (read this).

Again, the purpose of these calculators and charts isn't to give the final verdict what is the best for you needs, but only to give you a suggestion in your quest for the final answer. This area isn't so simple it might look on the first sight, it requires a tire professional with an experience and testing on the site(a tire service). So, be careful.


Table columns headings:

  • Column "Diff" may have percentages in the range from -3% to +4%(+5% for Winter tyres), which are allowed. Its value represents the ratio of the difference between OT and OE tyre diameter and the difference between OE tyre and OE wheel diameter, presented as percentage(%). In other words, it says what is acceptable deviation of the OT tyre diameter from the OE tyre diameter.
  • Column "Winter tyres only" that has an asterisk in a table row, means that the row tyre size is acceptable only for winter tyres.

Tyre interchangeability is not always possible, so be sure to consult your car manufacturer's manual before changing your tyres. This is for informative purposes only.

When practicing Plus Sizing methods, changing tyres and wheels, please pay special attention to the following: wheel size, i.e. wheel diameter, width and offset, tyre construction (Radial or Bias-ply), tyre speed rating, load capacity and maximum inflation pressure.

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