Outer Limits 4x4 Board

Hey, could one of you tyre gurus out there put up a conversion from 15" imperial to the 16" metric. for a tyre iliterate person like me
Eg what metric sizes for.

31 x 10.5 x 15 =

33 x 12.5 x 15 =

35 x 12.5 x 15 =

Cheers.
Dave.

265/75R15

315/75R15

315/85R15

There are other options but you're mainly looking at:

245/75/16 = 31" (30.5" nominal)

Note this is an unusual tyre size and 265/70/16 is the normal 31" replacement - about 31x10.5x16


265/75/16 = 32" (31.6" nominal) Pretty common.
About a 32x10.5x16

235/85/16 = 32" (31.7" nominal)
More a landrover/narrow rim size. About a 32x9.5x16

7.50R16 =32" (Nominal 31" + tread) Common split rim.


285/75/16 = 33" (32.8" nominal)
Very common. About a 33x11.5x16

255/85/16 = 33" (33.1" nominal)
More a landrover/narrow rim size. Similar to 33x10.5x16

305/70/16 = 33" (32.8" nominal)
The nearest equivalent to a 33x12.5x16.

315/75/16 = 35" (34.6" nominal)
Similar to 35x12.5x16

280/85/16 = 35" (34.8" Nominal)
35x11.5x16


These are most of the common sizes - there are heaps of options but a few of them are pretty rare and expensive.


All but the splitty (6" rim) are normally an 8" rim recommendation. The 235 is a 7" rim recommendation.



Theres plenty of tyre calculators out there but basically it comes down to section x aspect + rim size

eg

285mm/25.4 = 11.22"

11.22 x 75% x2 (both sides of the rim) = 16.83"

+ 16" for the rim = 32.83"


Thats how the measurement for the 285/75/16 is nominally calculated.


You will find that regularly metric tyres are a little over nominal, where generally most common 4wd imperial tyres are undersized - eg a 31" is normally about 30.6"new , and can at least be as small as 30.1" legally.


Obviously they can lose a lot of height overwear..... 17mm of tread off each side to a bald tyre means more than an inch shorter.

Beastmavster wrote:There are other options but you're mainly looking at:

245/75/16 = 31" (30.5" nominal)

Note this is an unusual tyre size and 265/70/16 is the normal 31" replacement - about 31x10.5x16


265/75/16 = 32" (31.6" nominal) Pretty common.
About a 32x10.5x16

235/85/16 = 32" (31.7" nominal)
More a landrover/narrow rim size. About a 32x9.5x16

7.50R16 =32" (Nominal 31" + tread) Common split rim.


285/75/16 = 33" (32.8" nominal)
Very common. About a 33x11.5x16

255/85/16 = 33" (33.1" nominal)
More a landrover/narrow rim size. Similar to 33x10.5x16

305/70/16 = 33" (32.8" nominal)
The nearest equivalent to a 33x12.5x16.

315/75/16 = 35" (34.6" nominal)
Similar to 35x12.5x16

280/85/16 = 35" (34.8" Nominal)
35x11.5x16


These are most of the common sizes - there are heaps of options but a few of them are pretty rare and expensive.


All but the splitty (6" rim) are normally an 8" rim recommendation. The 235 is a 7" rim recommendation.



Theres plenty of tyre calculators out there but basically it comes down to section x aspect + rim size

eg

285mm/25.4 = 11.22"

11.22 x 75% x2 (both sides of the rim) = 16.83"

+ 16" for the rim = 32.83"


Thats how the measurement for the 285/75/16 is nominally calculated.


You will find that regularly metric tyres are a little over nominal, where generally most common 4wd imperial tyres are undersized - eg a 31" is normally about 30.6"new , and can at least be as small as 30.1" legally.


Obviously they can lose a lot of height overwear..... 17mm of tread off each side to a bald tyre means more than an inch shorter.

Cool, but he was after 15 inch rims..............

Read it again LOL... he wanted a conversion from 15" to 16".


Anyway to give you an ideas what I mean about sizing.. this is basically data off the Nankang mud tyre thread and using 32" as an example.

http://www.nankangtyres.com.au/prodDetail.php?pid=21


Note the diameter of the 265/75/16 = 806mm or 31.73" Slightly over nominal... but the 32x11.5x15 is smaller at 791mm or 31.14".

The Narrow metric (235/85) option is also 804mm.

Very common for the metric equivalent to be significantly bigger than the imperial. Both of these 32" equivalents are noticably larger back to back. It's not much, but it's there.... another 7mm of ground clearance for nothing aint to be sneezed at.


Likewise the 285/75 is 32.8" but the 33" is only 32.1". In my coopers the 285/75 was meant to be 33.1" and I've seen them as big as 33.3" from other manufacturers.

They can be an inch bigger than the equivalent metric and still be marked as say a 33". Just what we want for 4wding.

This occurs across pretty much all brands and was a significant factor in me choosing 16" rims.




75 Series

75 16" LT315/75R16 121Q 8.5" 873 317 E0226
75 16" LT285/75R16 122/119M 8.0" 834 286 E0224
75 16" LT265/75R16 112/109N 7.5" 806 266 E0222
75 16" LT245/75R16 108/104N 7.0" 774 254 E0221
75 15" LT235/75R15 104/101Q 6.5" 733 238 E0220

85 Series

85 16" LT235/85R16 120/116N 6.5" 804 242 E0227

100 Series

100 15" 33*12.5R15LT 108Q 10.0" 816 316 E0219
100 15" 32*11.5R15LT 113Q 9.0" 791 296 E0218
100 15" 31*10.5R15LT 109Q 8.5" 774 272 E0217

D'OH!!!!

http://members.optusnet.com.au/~zerosin/gearcalc.html

Heaps of info and calculators.

Thanks for all your replys. They are very helpfull. I will know what I am looking at when looking for tyres now.
Cheers.
Dave.

Sh1t,


Did I give some good tech to someone?

Beastmavster wrote:Sh1t,


Did I give some good tech to someone?

Erm... I know I didn't

(Note to self: 1/2A = RTFQ)

Beastmavster wrote:Sh1t,


Did I give some good tech to someone?

Sure did. Thanks mate.
Unless you are leading me up the garden path that is. lol
Cheers.
Dave.

If you dont mind my asking - what rig is it for?


The benefits in determining my choice of a 16" were:
Better onroad handling/braking/fuel economy
Reduced weight = less chance of axle/cv breakage
Narrower tyre better in mud
Narrower tyre easier to clear guards
Larger diameter = more ground clearance than imperial equivalent
Looks more "stock" when larger tyres fitted

Downsides are:
Not as good on beach (narrower)
More expensive for rims and tyres
Secondhand tyres rarer
Harder to get in remote areas (other than 7.50R16 of course)

For a zook a 7.00R16 is pretty much ideal IMHO. If you could score them easily I'd love 8.50R16 (max legal under new laws and over 34"). 8.25 is rare ina muddie profile though.

9.00R16 is an awesome size too. I'd love some old army style 9.00R16 as weekend tyres... they look like Jungletrekkers.

Beastmavster wrote:If you dont mind my asking - what rig is it for?


The benefits in determining my choice of a 16" were:
Better onroad handling/braking/fuel economy
Reduced weight = less chance of axle/cv breakage
Narrower tyre better in mud
Narrower tyre easier to clear guards
Larger diameter = more ground clearance than imperial equivalent
Looks more "stock" when larger tyres fitted

Downsides are:
Not as good on beach (narrower)
More expensive for rims and tyres
Secondhand tyres rarer
Harder to get in remote areas (other than 7.50R16 of course)

For a zook a 7.00R16 is pretty much ideal IMHO. If you could score them easily I'd love 8.50R16 (max legal under new laws and over 34"). 8.25 is rare ina muddie profile though.

9.00R16 is an awesome size too. I'd love some old army style 9.00R16 as weekend tyres... they look like Jungletrekkers.

It is for a midi landcruiser. I will probably be going 16" for some of the reasons that you mentioned and also I am going to put an 80 series chassis under my midi, and I have been told that only 16s fit over the brakes. I was asking about conversions because I understand imerial sizes but had no idea of the metric equivalent.

OK...

Later Patrol had the same issue... you have to use 16" to clear rims (or shave a little off).

Rather just buy the rims and be done with it the safe and legal way.

16"s in bigger sizes are becoming more common, especially now Prados and the like are going to 17"s as an option. But traditionally there's a long history of big rubber in 16"s going back to WWII.

There's a couple of really good muddie options actually in 16 - simex, silverstone, swampers etc. It's quite possible to get both all round tyres and hardcore rubber.

9.00R16 is an awesome size too. I'd love some old army style 9.00R16 as weekend tyres... they look like Jungletrekkers.

Got any pics of these tyres, they sound interesting?

Matt

These are michelin XML 9.00R16.

Be careful because they're actually about 37" rubber...




Michelin XL 9.00R16

The old style bar type tyres do still exist because they get used on old military vehicle restorations. There's some sitting on a cannon down the road from me so I should grab a photo of them and host them up.