Tyres question

[AndrzejM]

Guys,
I need to buy new set of tires and I'm wondering what size I should buy

Original size is 195/60/15

Two possible options:
195/65/15
185/65/15

diameter (mm) diameter difference (mm) difference (%)
615 mm 0 mm 0 % 195/60/15
634.5 mm 19.5 mm +3.07 % 195/65/15
621.5 mm 6.5 mm +1.05 % 185/65/15

First option - taller tire so revs are going down, but car is higher and frontal area is increased
Second option - narrow tire so frontal area is smaller but revs 2% lower than with first option.

Which option in your opinion will be best for FE?

[gone-ot]

A tall, thin tyre will help fuel economy the most, with least increase to CdA.

Remember, think about the RATIO of tyre area vs. vehicle area...tyres are significant, but not HUGE in comparison.

[CapriRacer]

If we ignore the affect the difference in diameter has on engine performance, then larger tires are better. This includes the affect on aero due to the larger frontal area.

I talk about the effects larger tires have on rolling resistance here:

Barry's Tire Tech

But be forewarned - the affects we are talking about are small. Careful selection of tires (make and model) will have much, much more affect than a change in tire size.

[euromodder]

195/65/15 will gain you 1cm where you can fit the belly pan

What tyres do you plan on getting ?

[AndrzejM]

Originally Posted by euromodder

195/65/15 will gain you 1cm where you can fit the belly pan

What tyres do you plan on getting ?

You are right! That's awesome!

Tyres, for now I have to buy a set of winter tyres, I'll try to find LRR ones, but that won't be easy within my budget.

[euromodder]

Originally Posted by AndrzejM

Tyres, for now I have to buy a set of winter tyres, I'll try to find LRR ones, but that won't be easy within my budget.

Nokian should have some good LRR winter tyres.

Michelin Alpin A4 is good too, but will probably stretch the budget

[touring21]

Just found this quote from Bridgestone about future tyre development
I also noted that Bridgestone has a newish tyre ecopia ep001s which has a EU label rating "A" for fuel economy and "A" for wet braking performance. Not available in Australia just yet

"Tokyo (March 5, 2013)-Bridgestone Corporation today announced the successful development of its new "Large & Narrow concept tire". The concept tire represents a new category of tire that is narrower and features a larger diameter than conventional tires. It was created as a new environmental technology to enable tires to help realize a sustainable society.
The Large & Narrow concept tire technology helps vehicles achieve improved fuel efficiency, thereby contributing to reductions in CO2 emissions. Moreover, the air pressure within these tires is higher than conventional tires, and the design includes new pattern technology and compounds designed specifically for use in these tires. The new brand of innovative technology employed in the Large & Narrow concept tire enables it to realize significantly lower levels of rolling resistance and substantially higher levels of wet grip performance.
The Company is advancing development of this technology with plans to quickly put it into practical use. Possible applications include use of the technology in a new category of tires to be incorporated into Bridgestone's ECOPIA line of fuel-efficient tires. This new tire technology may be introduced as original equipment on next-generation automobiles or other vehicles.
The Large & Narrow concept tire will be displayed at Bridgestone's booth at the 83rd International Motor Show -Salon de l'auto de Genève to be held in Geneva starting March 5, 2013.
As the world's leading tire manufacturer, the Bridgestone Group is working towards 100% sustainable material usage and reducedCO2 emissions through improved fuel efficiency. We believe that this will make it will possible for us to continue providing world class tire products that are also sustainable from both a business perspective and environmental perspective. Going forward, the Group will push ahead with the development of various technologies geared toward contributing to the realization of a sustainable society.
CHARACTERISTICS OF THE NEW TECHNOLOGY
1. Environmental Performance
By giving tires a larger vertical diameter and increasing their internal air pressure, it is possible to greatly limit changes in the shape of the contact patch, the section of the tire that comes in contact with the ground. Further, by optimizing the structure of tires created using this technology and using the most appropriate materials, we achieved a rolling resistance coefficient that is approximately 30% lower than conventional sized tires (175/65R15). Further, making tires narrower reduces air resistance, a major factor that needs to be considered when working to improve fuel efficiency. Due to these features, tires that employ this new technology are able to boast levels of fuel efficiency exceeding those of the fuel-efficient tires Bridgestone has already put on the market.
2. Safety
The narrower size of tires made with this technology helps reduce the pressure placed on the tires by water present on roads when driving during rain or under other wet conditions. In addition, the tires have been specially designed to have a longer contact patch and higher contact pressure, which helps these tires prevent water from accumulating between the tire and the road. These features combined with the benefits of the tires' newly developed, specialized patterns and compounds enable the tires to achieve an improvement in wet grip performance of approximately 8%in comparison to conventional tires, thereby enhancing safety.
Reference
The development of the Large & Narrow concept tire is one of Bridgestone's initiatives to achieve the goal of "contribute to globally agreed target (50% reduction in CO2 emissions)" defined for the Group's efforts toward "reducing CO2 emissions" in its long-term environmental vision"

[Saks]

Last semester we have learned about tyres, and tyre dimensions. And in theory it says, lower tyre profile and wider = lower rolling resistance, higher tyre profile = higher rolling resistance.

Here is a picture of the difference betwen high profile, and low profile tyres


As you can see the the wider and low profile tyres have less surface contact (I don't know hot so speel it right because my English is still not that good, and I know that now sounds like the wider tyres are less safer than thyn tyres, but I hope somebody will get my point )

[LeeD]

Touring21 and Saks, thank you for taking the time to share this information!

[LeeD]

Cześć!
Andrej, independent of the width, I would buy the best rolling resistant tire you could afford. I am not sure what is available in Polska, but the research I have done tells me that Michelin Energy Saver A/S is the best you can buy. Because I am still new here, I can not post a link to the review that compared it's mpg to other tires, but it was significantly better than the others in the LRR tire category.