Wheel/tyre size

Wheels, Tyres, Suspension, Chassis
DeeR
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Wheel/tyre size

Post by DeeR » Thu Aug 04, 2016 11:19 am

Hello, greeting from sunny Croatia,
I have a BlueHDI 100 fitted with wheel/tyre 205/50 R 17" (CROSS 17"). Is there anyone who can explain to me the practical difference between this wheel/tyre size, and a smaller size of 200/55 R 16" or 195/65 R 15" that are also fitted on Cactuses. Difference in fuel consumption? road stability? ground clearance? .... ??? Some believe that the ride is smoother with smaller wheel size. My brother just commented: oh, this is gonna be expensive to change one day.
I was not going for any specific wheel size or shape, the car was purchased as exhibited in the Citroen shop.
Otherwise, I seem to have chosen a perfect car for my character and temperament, so far (4000 km) excellent experience (apart form the initial spontaneous or "spontaneous" unlocking - which does not happen any more :P ).
Blue lagoon/Habana inside C4 CACTUS Shine (Flair) BlueHDI 100 S&S


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BristolRich
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Re: Wheel/tyre size

Post by BristolRich » Thu Aug 04, 2016 1:50 pm

As a start the 17" tyres are more expensive in comparison than the 16's...

The rolling diameter will be near identical.

A smaller wheel will turn in quicker but on a car like the Cactus the difference will be negligible.

Smoother....subjective. One persons perception of comfort is someone else's discomfort.
Ex - 2014 Hello Yellow Citroën C4 Cactus Hatchback 1.6 BlueHDi 100 Feel Edition


DeeR
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Re: Wheel/tyre size

Post by DeeR » Thu Aug 04, 2016 2:28 pm

Got it. But then , why do they fit different wheel/tyre sizes on the same car?
Blue lagoon/Habana inside C4 CACTUS Shine (Flair) BlueHDI 100 S&S


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Softrider
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Re: Wheel/tyre size

Post by Softrider » Thu Aug 04, 2016 3:32 pm

The difference in rolling diameter is by law restricted to +/- 5% (at least here in Denmark). The reason for having different wheel/tyre sizes is primarily the width of the tyre. Wider tires will usually mean more rolling resistance and the car will therefore also usually consume more fuel. Another aspect is the sidewall height of the tyre (the height of the rubber part of the wheel if you like). If you're using 205/50-17 tires the height of the sidewalls will be 50% of 205 mm which is 102,5 mm or 10,25 cm. If you're using 195/65-15 tires the height of the sidewalls will be 65% of 195 mm which is 126,75 mm or aprox 12,68 cm. A greater height or more rubber usually mean less road noise and better comfort (the taller sidewalls will let the tires flex more), but as BristolRich points out... one persons perception of comfort is someone else's discomfort. :)
Citroën C4 Cactus BlueHDi 100 (since August 2014)
History: 2002 Citroën C5 2.0 HDi with Hydractive 3


DeeR
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Joined: Sat Jul 16, 2016 7:02 am

Re: Wheel/tyre size

Post by DeeR » Thu Aug 04, 2016 5:50 pm

Thanks, but forgive my ignorance: What is the point to fit a 205/50 R 17" tyre, instead of 195/65 R 16"?
Just to increase consumption, decrease the agreeableness of the ride and impose a higher price?
Blue lagoon/Habana inside C4 CACTUS Shine (Flair) BlueHDI 100 S&S


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BristolRich
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Re: Wheel/tyre size

Post by BristolRich » Thu Aug 04, 2016 6:00 pm

DeeR wrote:Thanks, but forgive my ignorance: What is the point to fit a 205/50 R 17" tyre, instead of 195/65 R 16"?
Just to increase consumption, decrease the agreeableness of the ride and impose a higher price?
Bigger wheels fill the arches - aesthetics

Bigger/smaller wheels suit certain wheel designs better than others...

Choice and a degree of customisation...

Market factors...

Smaller wheels work better in colder climates e.g. snow...

The difference between the two tyre size options is marginal if any real world difference and their impact on the vehicle performance negligible.
Ex - 2014 Hello Yellow Citroën C4 Cactus Hatchback 1.6 BlueHDi 100 Feel Edition


DeeR
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Re: Wheel/tyre size

Post by DeeR » Thu Aug 04, 2016 6:12 pm

So I am left with one possible advantage of a bigger wheel: riding stability in non-icy/snowy weather conditions (?).
Blue lagoon/Habana inside C4 CACTUS Shine (Flair) BlueHDI 100 S&S


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Softrider
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Re: Wheel/tyre size

Post by Softrider » Thu Aug 04, 2016 6:23 pm

I find the difference between the two tyre sizes significant when it comes to ride comfort, but again that's a personal opinion. The unsprung weight of the 17" wheels on the car is also higher than with 15" wheels. Less is more and all the better for the road handling on normal roads and speed, but on the german autobahn in 140-150+ Kph the 17" wheels offers way better stability and safety. The 16" wheels might be a good compromise in this regard. :)
Citroën C4 Cactus BlueHDi 100 (since August 2014)
History: 2002 Citroën C5 2.0 HDi with Hydractive 3


DeeR
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Re: Wheel/tyre size

Post by DeeR » Thu Aug 04, 2016 7:26 pm

I am not at all a fan of German Autobahnen and connected racing habits, but, rather, a soft rider, like you, I presume. A wider tyre contact with the road must in some way increase the stability of the car, while, at the same time, the alloy of the wheel contribute to lower unsprung weight, so possibly not affecting the comfort of the ride.
In any case, my CACTUS happens to be the most comfortable and fuel saving car I have had so far (Renault 4, Yugo, Megane 1997, Scenic 2001).
Blue lagoon/Habana inside C4 CACTUS Shine (Flair) BlueHDI 100 S&S


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Muddles
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Re: Wheel/tyre size

Post by Muddles » Mon Aug 22, 2016 3:04 pm

My dealer told me that if I replaced my 17" wheels with the 15" wheels my car (Blue HDi Flair) would actually do 93mpg, whereas with the larger wheels this is not possible, and with 16" and 17" wheels the fuel consumption is a lot more.

I have no idea why having a 15" wheel would make the car more economical but it does state that in the advertising leaflets not sure if it's in the handbook, not looked.

I'm also not clear if this just affects diesels or whether the petrol models are included.
2015 1.2 Puretech 82 Feel - Obsidian Black with Black Bubblewrap - 16" Square Alloys


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