Tire size interchangeability

It often happens that the required tire size is not available or a very similar size with similar parameters is significantly cheaper. Immediately, the question arises: what will happen if the sidewall is slightly higher and instead of the required size 205/55/16, we install 205/60/16. Today, we will thoroughly discuss such replacements and the associated risks. 

First of all, it is necessary to understand the values of the size marking. The correct understanding of this depends not only on the applicability of the tire but also on safety in general. 
205 - profile width in millimeters 
55 - profile height as a percentage
16 - mounting diameter in inches. 

It is precisely because some car enthusiasts do not take into account that the profile height is indicated as a percentage, which sometimes leads to serious errors. Here, everything depends on the profile width. If we are talking about the size 205/55/16, then the profile width "55" will be equal to 112 mm, and if we consider the size 275/55/20, the same value "55" will mean a profile height of 151 mm. Therefore, it is essential to rely on the profile width recommended for your vehicle. 

Now, let's consider the tolerances that are possible. The automaker allows the installation of tires with a tolerance of ± 3% of the outer diameter of the tire. In theory, such tires can be installed without consequences. BUT there are nuances. For some cases, this option is not applicable. 

205/55/16 - 632 mm - recommended size 
205/60/16 - 652 mm (+3%) within the upper tolerance limit. 
205/65/16 - 672 mm (+6%) is not permissible

It should be particularly noted that when replacing the size, the characteristics of the vehicle change. The speedometer shows an incorrect speed because the wheel circumference has changed. With an increase in profile height, the vehicle holds its course stability worse and is more prone to skidding. 
Vehicles that require homologated tires are entirely outside of these rules, as they have a tolerance of only 0.5%. Otherwise, even if the tires fit, the safety system may not accept the tire with new parameters and regularly lead to the appearance of errors and emergency activations of ESP systems. 

It is best to refrain from replacing the recommended size. The automaker takes into account a mass of factors, such as the weight of the vehicle, the length and height of the body, and dynamic characteristics. When measuring the recommended tire size, unforeseen problems with safety or handling may arise.