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OEM Tyre sizes and alternatives


fabdavrav

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Thought I would collate and put into plain english the basic info required for sizing the tyres into one place, as there seems to be lots of info scattered all over the place and some of it was missing!

Roomster OEM Sizes

185/60 R15 84T

195/55 R15 85H

205/45 R16 87W

205/40 R17 84W

What does it mean??

195/55 R15 85H

195 = 195mm width of tyre

55 = 55% of the width equals the depth of the sidewall (aspect ratio)

R15 = Radius of the alloy or steel rim in inches (15") that the tyre fits

85 = Load index rating of 515kgs

H = Speed rating max of 130mph

Tyre load rating table link

http://www.tyresave....k/tyreload.html

Tyre speed rating table link

http://www.tyresave....k/tyrspeed.html

What about a different tyre? Will it fit if not listed as OEM??

Yes it will so long as the R/C (rolling Circumference) is no more than 2.5% bigger or smaller than the OEM size. This is so that it does not make the speedo mis-read and cause problems with the ABS/ESP systems, gearing, insurance, etc, etc!

OEM sizes

185/60 R15 has a R/C of 1894.38mm....-2.5%= 1847.02mm....+2.5%= 1941.74mm

195/55 R15 has a R/C of 1870.82mm....-2.5%= 1824.05mm....+2.5%= 1917.59mm

205/45 R16 has a R/C of 1856.37mm....-2.5%= 1809.96mm....+2.5%= 1902.78mm

205/40 R17 Has a R/C of 1871.76mm....-2.5%= 1824.97mm....+2.5%= 1918.55mm

Other sizes within 2.5%, not all are standard tyre sizes done by all manufacturers!

185/65 R14 R/C = 1872.70mm

185/55 R15 R/C = 1836.26mm

205/50 R15 R/C = 1840.97mm

195/50 R16 R/C = 1889.35mm

215/45 R16 R/C = 1884.64mm

215/35 R17 R/C = 1829.35mm

215/40 R17 R/C = 1896.89mm

225/35 R17 R/C = 1851.34mm

215/30 R18 R/C = 1841.60mm

225/30 R18 R/C = 1860.45mm

235/30 R18 R/C = 1879.30mm

Tyre size calculator link

http://www.alloywhee...om/tyrecalc.asp

EDIT

I will be adding info to this as and when I get time! emoticon-0103-cool.gif

Edited by fabdavrav
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  • 4 years later...

Hi,

 

Your Fabia thread has even more info for Summer wider and Winter narrower choices, and also temp. change adjustments e.g.winter pressures.

 

http://www.briskoda.net/forums/topic/217351-oem-tyre-sizes-and-alternatives/

 

Thanks

 

From the Roomster Owners Manual

 

Snow Chains

 

For technical reasons, it is only permissible to fit snow chains with the following
wheel/tyre combinations.

Wheel size - Depth (D) - Tyre size
5J x 14 - (D 35 mm)  - 175/70
6J x 14 - (D 37 mm) - 185/65
6J x 15 - (D 43 mm) - 185/55

 

Only fit snow chains with links and locks not larger than 12 mm.
Remove the full wheel trims before installing the snow chains.
Observe the national legal regulations relating to the use of snow chains and the
maximum vehicle speed with snow chains.

 

CAUTION
The chains must be removed when driving on roads which are free of snow. They
adversely affect the handling of your vehicle, damage the tyres and are rapidly
destroyed.

 

Ð - Bold indicates Faclift Roomster with min. 15" Wheel size.
 

Edited by petrev
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  • 2 years later...
On ‎27‎/‎10‎/‎2011 at 11:34, fabdavrav said:

What does it mean??

195/55 R15 85H

195 = 195mm width of tyre

55 = 55% of the width equals the depth of the sidewall (aspect ratio)

R15 = Radius of the alloy or steel rim in inches (15") that the tyre fits

85 = Load index rating of 515kgs

H = Speed rating max of 130mph

Tyre load rating table link

http://www.tyresave....k/tyreload.html

Tyre speed rating table link

http://www.tyresave....k/tyrspeed.html

 

Some not quite correct info, and some fundamentally wrong info.

 

What does it mean??

195/55 R15 85H

195 = 195mm is the nominal section width of tyre in millimetres (and not the actual tread with); the actual figure can vary from one tyre manufacturer to another

55 = this is the aspect ratio, specifically the height of the sidewall is 55% of the nominal section width 

R = a tyre of radial ply construction (as opposed to either cross-ply or bias belt)

15 = diameter of the vehicle roadwheel (alloy or steel) in inches (15") that the tyre fits

85 = Load Index rating; up to a maximum mass (per tyre) of 515kgs

H = Speed Rating; up to a maximum vehicle speed of 130mph

 

It must also be stated that when upgrading or changing tyres and / or roadwheels, it is a legal requirement that you must never go below the OEM Load Index and Speed Rating figures.  If you do go below either or both, you will void your insurance, and could be liable for a criminal prosecution for breaching Construction and Use Regulations.  It is perfectly legal (and safer) to fit tyres with a higher Load Index and / or Speed Rating.

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& if you fit a Tyre Size, Speed Rating / Load rating that the Manufacturer gives for a Winter / Snow Tyre, or wheels / tyres with Snow chains you are perfectly legal.

Perfectly OK with Insurers.  MOT, DVSA, Police etc etc.

 

Just ask a Broker / Underwriter when Winter / Snow tyres are suitable in the UK, and they might say October to March.

but this is April and snow is forecast, and there can be low temps any time of the year in parts of the UK, or even snow / ice when is is British Summer Time according to Clocks / Calendar, then people can take their vehicle out of the UK to places where winter tyres are still required in what would be considered the UK Summer.

But never go lower than the Minimum Speed / Load ratings....

Edited by Skoffski
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