How to Know which Wheel/Rim Sizes for your Car

By David Barlow
Last Updated: September 14, 2021
which WheelRim Sizes for your Car

Changing the rim size: which rims for my car?

Many of you ask yourself:

  • what dimensions are legal for my car? will i be insured in the event of an accident? does it go through technical control?
    Let’s answer a first question for neophytes:
  • when do i change the wheel/rim size?

When winter arrives, when we change the diameter to have smaller tires: in addition to being economical, this solution has the advantage of giving thinner tires, which in winter guarantees more grip on the ground and therefore more safety.
Conversely, it is usual to switch back to summer tires and at the same time to larger rims, in order to have wider tires, and thus increase stability on the ground (yes, it is a bit the reverse of Winter…).
Also, it may simply be a desire, a question of aesthetics, the switch from sheet rims to aluminum rims, the recent purchase of a car that is just begging to be pampered, etc. We then wonder how far we can go, within the limits of the law and approvals.
You had the rather modern reflex of searching the internet for the size of rims that you can put on your car. This is also what I would have done. But the possible dimensions may vary depending on the model, version, year, etc., it is better to check the base first:

The indications present on your vehicle

Inside the door, next to the pressure indications, inside the tank, etc. But above all, in the technical booklet of the vehicle. Yes Yes ! This is where you have to start your research!

Note that you will find on your vehicle the mounts approved by the manufacturer. Choosing one of the dimensions that you find there is the guarantee of not having any surprises and of passing the technical control without problem, and of being insured.

But you might want more. Yes, I know you! You thought you could put on 18 ″!

In fact, the legislation also authorizes conversions and offers the possibility of equipping vehicles with tires different from those recommended by the manufacturer.

Remember that the outside diameter of the tire must be the same. The dimensional equivalence table formerly published by manufacturers is now replaced by an official table published by the TNPF (French Pneumatic Standardization Works) which is valid with the authorities and technical control.

This table allows for example the following oversizing from a 195/65 R 15 >>>> 205/55 R 16> 205/50 R 17> 225/45 R 17> 225/40 R 18> 245/35 R 18> 255/30 R 19> 305/25 R 19
This example clearly shows that in order to be able to increase the size of the rim, it is necessary to fit increasingly smaller tires. And it also shows that the tires are getting wider and wider. In images, in pictures :

increase the size of the rim
increase the size of the rim

Both on the technical and regulatory aspects, 3 precautions should be taken:

  1. Load and speed ratings must be equal to or greater than those of the original equipment. This is an absolute requirement for the equipment to be legal and for the vehicle to be covered by insurance.
  2. The rim width must be compatible with that of the tire. Manufacturers have a “mini – maximum rim width” table corresponding to each tire size. The intermediate nominal value is the recommended width so that the tire is ideally positioned on the rim and can work in the best conditions.
  3. The fender passages must be able to accommodate a wider tire.

Last check, our rim search engine for your vehicle, coordinated with our vehicle search engine: you enter the model of your vehicle, then you choose a rim diameter, then the tires.

Warning: the new technical inspection applicable since May 20, 2018 indicates that a rim or a tire protruding from the bodywork results in a refusal and implies a follow-up inspection after re-compliance.
In addition, a tire whose characteristics (load index and speed symbol) are insufficient for the actual use of the vehicle results in the classification as critical failure with the consequence of immobilizing the vehicle.

David Barlow

Automotive Experts at World Tire Review

Hi everyone, I’m David (Tireguy). I believe that finding tires can lead to a lot of confusion and frustration for almost every driver. That’s why I would like to bring my experiences and knowledges to develop World Tire Review blog, it will give people a deeper understanding of what choosing the right tire is really like!