Increased dimensions of pneumatic cars ??

[laurent_caen]

Hi,

I have been wondering for some time about the dimensions of car tires, which are only increasing. For example :
- the 406 2.0 HDI 110hp, 1395 kg unladen according to manufacturer data -> tires: 195/65 R15
- the 407 1.6 HDI 110hp, 1441 kg -> tires: 205/60 R 16
- the 508 1.6 HDI 112hp, 1405 kg -> tires: 215 / 60R16 (base) and option: 215 / 55R17 or even 235 / 45R18 !!!!

What is the point of having such tire sizes when it penalizes consumption, comfort ...?

I do not understand at all this completely insane increase in dimensions for tires with all other characteristics being equal! If anyone sees an explanation if there is one ...

Good night

Laurent

[Flytox]

The first must be aesthetics, it's "sport", it's sales. A lot of car advertising is based on performance, speed, they want us to believe it's better. So it has to look like Loeb or Vettel's car ....

[Grelinette]

For the same vehicle speed, a large wheel allows an engine to run slower. On the other hand the engine must be more powerful.

My hypothesis is that depending on technological progress, it may be easier and more economical for manufacturers to make a powerful motor which rotates slower than the opposite! ...

[laurent_caen]

For the same vehicle speed, a large wheel allows an engine to run slower. On the other hand the engine must be more powerful.

Yes, but here we are talking about 3 engines of identical power! I do not understand, especially since even the "optimized" version of the 508 with stop & start wanting to be the most "green" is fitted with such huge wheels!

[Christophe]

For the same vehicle speed, a large wheel allows an engine to run slower. On the other hand the engine must be more powerful.

We are talking about the width ... not the diameter!

On a 16, 17 or 18 inch rim, the rolling diameter is roughly the same ...

Also, I do not agree about comfort: wider wheels improve comfort (road noise) and handling at higher speed (but when it really slips, it starts faster because larger surface therefore less pressure so we come out faster from the friction cone ...).

Here is a topic about tire marking: https://www.econologie.com/forums/savoir-lir ... 10843.html

Otherwise, except against written indication (= manual), we can very well put 195 tires on a vehicle delivered with 215 right? Especially if the chassis is the same !!

[I Citro]

Otherwise, except against written indication (= manual), we can very well put 195 tires on a vehicle delivered with 215 right? Especially if the chassis is the same !!

Only if the rim width is compatible ...
Very often it can hardly bear to get away from the climb for which it is intended and this phenomenon is amplified with low waist tires which tend to give trapezoidal profiles of the blanks if one climbs less wide.

The rim / tire seal is degraded and the rim flange is much more exposed to shocks (against sidewalks, in particular).

When I look for aluminum rims for my cars, I always have difficulty finding a reasonable width (I hate hubcaps which should be banned, because they regularly litter the roads and represent a significant danger of falls for bikers. , not to mention pollution).

[Christophe]

Ah yes good note, I just checked: this would probably require a change of rims ... to be negotiated when buying the vehicle (if new) ...

So I should have said "wheels"

[phil53]

(I hate hubcaps which should be prohibited, because they regularly litter the roads and represent a significant danger of falls for bikers, not to mention pollution).

Yes, it's a scandal, it pisses me off regularly

[Macro]

I'm going to bump into mounting tires on an optional 206 hdi 205/45/17 ...
When you fall into dimensions like that the dismantling and reassembly of the tire is complicated ... You can't know .... In the car center they take a few more euros per tire (it makes their bizness work) . To have the most reasonable ride on a car ask the ride of the commercial model with the same engine ...

Namely the low size tires of the 50/45/40 type are very fragile on the sidewall and the little deformation they have in normal use cause deformation of the rims (especially aluminum) at the slightest impact (mount a "boat" too quickly to park may be enough ...

the hubcaps when they are well designed we do not lose them. (try to tear off a chrysler hubcap serie 2 you will understand) ...

The aluminum rims ... Yeah so, Balancing I am really very surprised at the extra weight that it represents an aluminum rim ... And even more surprised at the imbalances that need to be corrected ... And even on original rims almost new (the last passat of my brother at 3 weeks a puncture behind the rim was balanced original with masses of 50 grams (after an optimization of the unbalanced tire rim (two launched balancer and two rotations of the tire after relaunch count 15 to 30 minutes) we still found ourselves at 30 grams ... In addition we must use bonded masses, with chemicals to clean ....

For me it is not worth a good old rim in Tole not expensive. The painted gray metal model goes very well with a hub cover in the middle. Zou ... Made simple and that we are not bored ...

[Gaston]

I do not understand at all this completely insane increase in dimensions for tires with all other characteristics being equal! If anyone sees an explanation if there is one ...

By increasing the width and diameter of the tire, the contact surface with the road is increased, therefore directly the road holding and the braking capacity (on dry roads).