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ahlidap Gate Opener
Joined: 06 Nov 2010 Odometer: 11

Posted: Wed Aug 08, 2012 8:27 am Post subject: Metric vs Imperial Tyre Size



Hi,
I've been searching the foruns, but I haven't found anything...
Basically, I can't figure how this is calculated...
I've always used 205/75 R15 on my NIVA, but I would like to return to the original 16" rims, but with a taller and wider tyre (when compared to 176R16).
So, I don't want a "BIG" lift in my NIVA to use 205R16 and don't want to loose mine ~7L/100Km ( 40 mpg? )..
According to baxters web site:
"The biggest tyres you can fit on a standard Niva are 195/80R (6.00x16) on the 16" rims"
This is exactly what I'm looking for!
But when I search for a formula, I always get to:
6.00x16...
width = 6"* 25.4mm = 152.4mm.....
err.. not 195 :/
Can you help me?
Is 6.00x16 , the same as 600R16 ?
Another "problem" is that, Brazilians say that 175R16 is the same as 6.95R16... so.. how could a 6.00R16 be wider??
I have a 50/50 tyre, and I think I would keep with it...
http://www.fedimatyres.com/pt/4x4/4x4/fronteira but with original rim
For offroad this is a very good tyre!
http://www.recippneus.com/epages/Store.sf/pt_PT/?ObjectPath=/Shops/RecipPneus/Products/%22RECIP%20TRIAL%22/SubProducts/%22RECIP%20TRIAL%20%206.00R16%22
And If you look on two, FEDIMA have 600R16 and RECIP 6.00R16.
Hope you can help me with this sizes
Thanks
PS:
Also found this table, that shows the 600R16 somewhere between the 175/80 R16 and 215/80 R15... so, probably the 195/80R16.
__________________________________ 1997 Lada Niva 1.9D Tinga
> Turbo e manifolds from Citroen ZX
> + 1/4 Diesel
> BackBox Exhaust out! 

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Xpajun Mud Obsessed
Joined: 22 Sep 2008 Odometer: 3241
1988 Mitsubishi Shogun

Posted: Wed Aug 08, 2012 9:38 am Post subject:



To convert:
divide the first number by 2.54 (gives you inches) this gives you the width of the tyre
Then multiply the width by the number after the slash as a % (i.e /75 = 75% or 0.75) multiply the result by 2 then add on the wheel size (if there is no number after the first then use 80% or 0.8 as the multiplier)
EXAMPLE:
205/75 R15
205 divide by 25.4 = 8.07086614 = tyre width
8.07086614 x 0.75 (75%) = 6.05314916 X 2 = 12.1062992 + 15 = 27.1062992
Rounding up the figures to the nearest .5" your tyres are 27 x 8 x 15


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Xpajun Mud Obsessed
Joined: 22 Sep 2008 Odometer: 3241
1988 Mitsubishi Shogun

Posted: Wed Aug 08, 2012 9:59 am Post subject: Re: Metric vs Imperial Tyre Size



ahlidap wrote:  Hi,
According to baxters web site:
"The biggest tyres you can fit on a standard Niva are 195/80R (6.00x16) on the 16" rims"
This is exactly what I'm looking for!
But when I search for a formula, I always get to:
6.00x16...
width = 6"* 25.4mm = 152.4mm.....
err.. not 195 :/
Can you help me?
Is 6.00x16 , the same as 600R16 ?
Another "problem" is that, Brazilians say that 175R16 is the same as 6.95R16... so.. how could a 6.00R16 be wider??

The 6.00x16 would indicate 6" wide by 16" wheel  at a 80% profile would equal a 25.6" tyre
Think baxters may be wrong
My calculations say that 175R16 is about the same as a 6.95R16 (standard aspect ratio is 80%) and that would give you a 30" tall tyre


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ahlidap Gate Opener
Joined: 06 Nov 2010 Odometer: 11

Posted: Wed Aug 08, 2012 10:32 am Post subject: Re: Metric vs Imperial Tyre Size



Xpajun wrote: 
The 6.00x16 would indicate 6" wide by 16" wheel  at a 80% profile would equal a 25.6" tyre
Think baxters may be wrong
My calculations say that 175R16 is about the same as a 6.95R16 (standard aspect ratio is 80%) and that would give you a 30" tall tyre 
Ok
This confirms the things on the web..
So, as you said, maybe the error is in the info given by baxters..
195/80 R16 are hard to find... at least with a 50 road / 50 offroad tread.
Thanks for your quick reply!
__________________________________ 1997 Lada Niva 1.9D Tinga
> Turbo e manifolds from Citroen ZX
> + 1/4 Diesel
> BackBox Exhaust out! 

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scrunt Articulating
Joined: 11 Jul 2012 Odometer: 985 Location: Tayside.

Posted: Wed Aug 08, 2012 2:24 pm Post subject:



Are you sure that 195 is the widest tyre the standard 16" rims can take,
have you measured the actual rim width?
You are going to posiibly lose some MPG anyway are you not, going to even keeping the same rolling radius but from a A/T tread to a Mud tread?
?? I think you were saying that you want to stay with an All Terrain style tread?
The one you show is like a Copy of the BF Goodrich all terrain tread and common here in remoulds. i used those myself in 195/80/15 (Colways)
195/75/16 Malatesta M&S
or 195/80/16 Mud tyres for taller.
http://www.tyresdirectuk.co.uk
Staying at the same width as 205/75/15
why not go 205/65/16, Not taller tho.
taller would be 205/80/16 which is probably too much for you.
http://www.kouki.co.uk/utilities/visualtyresizecalculator
http://www.camskill.co.uk
george


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baxter Articulating
Joined: 08 May 2006 Odometer: 647 Location: Dunedin, New Zealand
1990 Lada Niva

Posted: Sun Sep 02, 2012 9:28 am Post subject: Re: Metric vs Imperial Tyre Size



Xpajun wrote:  The 6.00x16 would indicate 6" wide by 16" wheel  at a 80% profile would equal a 25.6" tyre
Think baxters may be wrong 
Off the top of my head Imperial tyres are measured in height not width (like metric tyre are), hence a 6.00x16 is a 12 (ie 6+6) + 16 = 28" tall tyre.
There should be a link to a couple of tyre calculators on my yre page that should answer above.
__________________________________ 1990 Niva 1600, 2" lift, LSD
www.ladaniva.co.uk/baxter Baxter's Temple of Niva Site
If you do not have anything to occupy yourself  buy a Niva. 

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Xpajun Mud Obsessed
Joined: 22 Sep 2008 Odometer: 3241
1988 Mitsubishi Shogun

Posted: Sun Sep 02, 2012 12:25 pm Post subject: Re: Metric vs Imperial Tyre Size



baxter wrote:  Xpajun wrote:  The 6.00x16 would indicate 6" wide by 16" wheel  at a 80% profile would equal a 25.6" tyre
Think baxters may be wrong 
Off the top of my head Imperial tyres are measured in height not width (like metric tyre are), hence a 6.00x16 is a 12 (ie 6+6) + 16 = 28" tall tyre.
There should be a link to a couple of tyre calculators on my yre page that should answer above. 
My calculations were based on the quote below  standard aspect ratio is (as far as I'm aware) 80%
The Numeric system is old and outdated and unfortunately not only difficult to convert (so you know what you're fitting) but the conversion has to be based on an assumption.
Quote:  Numeric
Earliest system, dates back to the 30’s when there were few tyre sizes available (or needed)
Example:
9.1515
9.15 is the section width in inches
15 is the rim diameter in inches
Notes:
 Using this system you can’t tell the OD of the tyre without knowing the Aspect Ratio
 In the 1950s and early 1960s, the standard aspect ratio was 8284%
 Around 1970, bias ply tyres moved to a 78% aspect ratio
 In the 70’s the "standard" aspect ratio dropped to 75%
 Today, Aspect Ratios of 65%, 60% and even as low as 35% are available.
 If you know the AR of the tyre in question you can calculate the OD as: (Section Width x Aspect Ratio) x 2 + Rim Diameter (eg. in the above example, if we knew the Aspect Ratio were 78%: (9.15 x 0.78 ) x 2 + 15 = 29.3" )
 If you don’t know the AR, the only way to tell the OD is to consult the manufacturer’s specifications. 
Incidentally I've found that so many of the online tyre calculators to be flawed that I no longer use them  nor would I advise anyone to use them. In addition the size written on the side wall of the tyre very often bears no relationship to the size of the tyre anyway, especially with remoulds and, sometimes, even with new tyres as well


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baxter Articulating
Joined: 08 May 2006 Odometer: 647 Location: Dunedin, New Zealand
1990 Lada Niva

Posted: Mon Sep 03, 2012 1:51 pm Post subject:



Ahh so it is a measure of width afterall. My ones must have had a close to 1:1 width to height ratio (except my tractor ones, which explains why they're 32 inch 6.0016s) hence they measure either way.
But yeah, not including aspect ratio on various Imperial tyre sizes would indeed make it impossible to know overall diameter, so to answer the op  it depends on the aspect ratio; ask the seller the overall diameter.
__________________________________ 1990 Niva 1600, 2" lift, LSD
www.ladaniva.co.uk/baxter Baxter's Temple of Niva Site
If you do not have anything to occupy yourself  buy a Niva. 

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lambert Articulating
Joined: 21 Nov 2009 Odometer: 751 Location: the crown subsistancy of yorkshire

Posted: Wed Sep 12, 2012 5:42 am Post subject:



600's 650's 750's etc are all 100% aspect ratio. So as to get different sizes overall the rim size was altered. Better way than all this metric garbage we have now
__________________________________ Oh, really? That is a pity. 

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scrunt Articulating
Joined: 11 Jul 2012 Odometer: 985 Location: Tayside.

Posted: Wed Sep 12, 2012 10:40 am Post subject:



http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3802
600, 650, 700, is that not 'mm'?
Is that not Metric garbage measurements.
Now 31", 33",35" etc, is Imperial i think,
12" to the foot and 36" to a yard. Good old British. The Empire & the Commonwealth, The Raj rule.
george


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Xpajun Mud Obsessed
Joined: 22 Sep 2008 Odometer: 3241
1988 Mitsubishi Shogun

Posted: Wed Sep 12, 2012 1:09 pm Post subject:



scrunt wrote:  http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3802
600, 650, 700, is that not 'mm'?
Is that not Metric garbage measurements.
Now 31", 33",35" etc, is Imperial i think,
12" to the foot and 36" to a yard. Good old British. The Empire & the Commonwealth, The Raj rule.
george 
600 = 6" 650 = 6.5" 700 = 7" george so imperial and very old as in 1930s era


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