History of 10.50-16 tyres

[Lang]

Andrew

The reason they did not fit was all the old tyres were basically 100 height ie height of the tyre is the same as the width. They had various specialist odd-ball heights but you would expect any normal tyre of the period to be equal height/width.

This construction was so standard across the auto industry that tyres used to be measured by height with no wheel size ie 30x3. Everybody knew that the tyre was the same height as width so they knew that the 3 inch wide tire would go on a 24 inch rim (height of tyre top and bottom subtracted from overall height.

When they started with radial they messed with profiles so your 265/75 is only 3/4 as high as it is wide. To match the !0.50 you would need a 265/100 which I doubt is made.

As you found out we are now forced to use over wide tyres to get the original height if we want something off the shelf or go to the few specialists around the world still building 100 profile bias construction tyres.

Lang

[Grant Bowker]

The AEDB design record gives outside diameters for 10.50-16 tires that vary by brand:
Pneumatic cross-country 37.4-38.2 inches (2% variation)
Pneumatic highway tread 37.0-37.6 inches
Run-flat cross-country 37.6 inches

[Andrew H.]

Originally Posted by Lang

Andrew

The reason they did not fit was all the old tyres were basically 100 height ie height of the tyre is the same as the width. They had various specialist odd-ball heights but you would expect any normal tyre of the period to be equal height/width.

This construction was so standard across the auto industry that tyres used to be measured by height with no wheel size ie 30x3. Everybody knew that the tyre was the same height as width so they knew that the 3 inch wide tire would go on a 24 inch rim (height of tyre top and bottom subtracted from overall height.

When they started with radial they messed with profiles so your 265/75 is only 3/4 as high as it is wide. To match the !0.50 you would need a 265/100 which I doubt is made.

As you found out we are now forced to use over wide tyres to get the original height if we want something off the shelf or go to the few specialists around the world still building 100 profile bias construction tyres.

Lang

Thanks Lang!
Thats good information I didn't know.
We are still working on a plan to get your tyres across the ditch (a friend has a large yacht)
Andrew

[Lauren Child]

Originally Posted by Lang

Andrew

The reason they did not fit was all the old tyres were basically 100 height ie height of the tyre is the same as the width. They had various specialist odd-ball heights but you would expect any normal tyre of the period to be equal height/width.

This construction was so standard across the auto industry that tyres used to be measured by height with no wheel size ie 30x3. Everybody knew that the tyre was the same height as width so they knew that the 3 inch wide tire would go on a 24 inch rim (height of tyre top and bottom subtracted from overall height.

When they started with radial they messed with profiles so your 265/75 is only 3/4 as high as it is wide. To match the !0.50 you would need a 265/100 which I doubt is made.

As you found out we are now forced to use over wide tyres to get the original height if we want something off the shelf or go to the few specialists around the world still building 100 profile bias construction tyres.

Lang

I hit this problem with 1050R20 being 75% hieght versus 1050-20. I'd assume the same is true for other sizes, with the "R" being shorthand for a lower profile.

[Ilian Filipov]

Thanks for your answers guys, you're really awesome!

[Lang]

Lauren

The "R" stands for RADIAL and is not a size indicator.

For instance, the very common 7.50x16 used on Landrovers, Landcruisers etc for 50 years was a 100 profile (height equals width) tyre.

The world moved on, so for about 20 years in the 70/80 period they designed a new radial construction tyre to match equal height and width of the old bias construction. They called it 7.50R16

As those old vehicles were superseded by modern types wanting wider profile tyres without increase in rolling diameter we started to see the width-height relationship change with percentage profile measurements.

For those old vehicles still operating, they now have to go to the 235/85x16 which is the same height as the old 7.50x16. The difference is that it is 235mm (instead of 7 1/2 now about 9 1/2 inches) wide but, only 85% of that in height, to achieve the same diameter as the old tyre.

All the various commercial tyres (and most car tyres too)of whatever size went through that progressive change.

Lang

[Tony Smith]

Originally Posted by Lang

Lauren

The "R" stands for RADIAL and is not a size indicator.

Lang

Almost universally, Radial tyres with R in the size are 78% aspect ratio.

[Lang]

Tony

Where abouts is the reference to that. I can't find it in the Tyre and Rim Association manual.

Not saying you are wrong but the manual says the difference between 7.50x16 and 7.50R16 is only 4mm overall height (within normal manufacturing leeway). Everything I can find says the old tyre is 100 aspect ratio making the "R" tyre the same.

Maybe some of the other sizes went with the 78%?

Of course that stand alone "R" measurement only applied to tyres in the transition period between bias and radial construction - you can still find a few sizes so marked being produced for older applications. I think the 8.25R16 is still in use with the little 3-5 ton Isuzus and Mitsubish/Hinos.

All tyres have "R" in the size now but it is preceded by the aspect ratio so has nothing to do with size eg 185/65R14

Lang

PS

I just measured the 8.25R16 tyres on my OKA. Exactly 8.25 wide and 8.25 high giving an aspect ratio of 100.

PPS

I went looking and found a 7.50R16 M&S pattern on a wheel. Measured exactly 7.50 X 7.50. Measured the 7.50X16 Military ND on my 1/2 ton Dodge - exactly 7.50 x 7.50

[gjamo]

There appears to be seveal alternatives here.

https://www.vrakking-tires.com/14-16...tegory=14&n=75