Tyre sizes - ER70s and today's tyre measurement standards

[Marts]

Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.

[Jason James]

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.

I once went into a tyre place and asked for an "ER70" for the LTD. The
tyre-guy said that is only part of the tyre size, indicating, as you have
correctly put it above, the aspect ratio of the tyre ie ratio of width vs
tyre side-wall-height or the wall heght is 70% of the width.

I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.

Agree that the missing numbers were in the region of 205mm wide.

Jason

[Athol]

Post by Jason James

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS
was the ER70. Does anyone here remember them and if so, what is the
equivalent in modern day tyre size? I'm thinking around 205/70x14, but it
might be narrower.

I once went into a tyre place and asked for an "ER70" for the LTD. The
tyre-guy said that is only part of the tyre size, indicating, as you have
correctly put it above, the aspect ratio of the tyre ie ratio of width vs
tyre side-wall-height or the wall heght is 70% of the width.

You're talking about the "belted bias" tyre sizing scale, which replaced the
earlier inch codes on "bias ply" passenger vehicles.

The first letter was a general tyre size, and the 70 is the profile. The
R indicated radial construction.

On the end of that, you need a speed rating and a rim diameter. A dash
(-) was used where the tyre didn't have a speed rating.

Try sticking ER70H14 or ER70H15 into google.

Then E78-14 and D78-14. That was a common "base model" tyre.

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.

There is no code in front of the ER.

Post by Jason James
Agree that the missing numbers were in the region of 205mm wide.

IIRC, the fact that a tyre size started with E didn't make it the same
section width. I'm pretty sure that an ER70H14 is actually wider than an
E78-14. There was a letter scale, which meant that a D78-14 was smaller
than an E78-14, but the scale was different for different aspect ratios.

If nobody else comes back with some dimensions, I'll dig through some old
books here and find them later.

[Toby Ponsenby]

Post by Athol

Post by Jason James

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or
GTS was the ER70. Does anyone here remember them and if so, what is
the equivalent in modern day tyre size? I'm thinking around 205/70x14,
but it might be narrower.

I once went into a tyre place and asked for an "ER70" for the LTD. The
tyre-guy said that is only part of the tyre size, indicating, as you
have correctly put it above, the aspect ratio of the tyre ie ratio of
width vs tyre side-wall-height or the wall heght is 70% of the width.

You're talking about the "belted bias" tyre sizing scale, which replaced
the earlier inch codes on "bias ply" passenger vehicles.
The first letter was a general tyre size, and the 70 is the profile.
The R indicated radial construction.
On the end of that, you need a speed rating and a rim diameter. A dash
(-) was used where the tyre didn't have a speed rating.
Try sticking ER70H14 or ER70H15 into google.
Then E78-14 and D78-14. That was a common "base model" tyre.

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common
tyre in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.

There is no code in front of the ER.

Post by Jason James
Agree that the missing numbers were in the region of 205mm wide.

IIRC, the fact that a tyre size started with E didn't make it the same
section width. I'm pretty sure that an ER70H14 is actually wider than
an E78-14. There was a letter scale, which meant that a D78-14 was
smaller than an E78-14, but the scale was different for different aspect
ratios.
If nobody else comes back with some dimensions, I'll dig through some
old books here and find them later.

If you do, see if you can find an 'admission' that pre-MetricScam tyres
were actually smaller than when the older size descriptions made a
comeback:-)

IMHO, a (say) 195/78/15 is a narrower tyre now than it was before semi-
closed coding was tried out on us.

Conspiracy theory?
Nah.
Just simple observation.

[Jason James]

Post by Athol

Post by Jason James

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS
was the ER70. Does anyone here remember them and if so, what is the
equivalent in modern day tyre size? I'm thinking around 205/70x14, but it
might be narrower.

I once went into a tyre place and asked for an "ER70" for the LTD. The
tyre-guy said that is only part of the tyre size, indicating, as you have
correctly put it above, the aspect ratio of the tyre ie ratio of width vs
tyre side-wall-height or the wall heght is 70% of the width.

You're talking about the "belted bias" tyre sizing scale, which replaced the
earlier inch codes on "bias ply" passenger vehicles.
The first letter was a general tyre size, and the 70 is the profile. The
R indicated radial construction.
On the end of that, you need a speed rating and a rim diameter. A dash
(-) was used where the tyre didn't have a speed rating.
Try sticking ER70H14 or ER70H15 into google.
Then E78-14 and D78-14. That was a common "base model" tyre.

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.

There is no code in front of the ER.

Post by Jason James
Agree that the missing numbers were in the region of 205mm wide.

IIRC, the fact that a tyre size started with E didn't make it the same
section width. I'm pretty sure that an ER70H14 is actually wider than an
E78-14. There was a letter scale, which meant that a D78-14 was smaller
than an E78-14, but the scale was different for different aspect ratios.
If nobody else comes back with some dimensions, I'll dig through some old
books here and find them later.

Well, blew that one :-). Thanx for the correction.

Jason

[Knobdoodle]

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.
Agree that the missing numbers were in the region of 205mm wide.

205?!!?
I reckon it was more like 185 for a HR-HQ steel rim.

[Toby Ponsenby]

Post by Knobdoodle

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.
Agree that the missing numbers were in the region of 205mm wide.

205?!!?
I reckon it was more like 185 for a HR-HQ steel rim.

Inclined to agree:-)

[Albm&ctd]

Post by Knobdoodle

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.
Agree that the missing numbers were in the region of 205mm wide.

205?!!?
I reckon it was more like 185 for a HR-HQ steel rim.

I still remember the '70s evil 4 ply 155 width made by the Bridgestone
Wheelbarrow Company from eel skins, banana peels and pork fat on some Jap
cars. We put mags and 175 on the Honda and wooo everyone commented how
wide they were. Back then 205 with flared guards would probably get you
defected off the road. My my how times change.

Al

[Jason James]

Post by Knobdoodle

Post by Jason James
I think this error came about because XX/ER70/14"s were the most common tyre
in radials for the "big 3" manufcturers with 6" or 6 1/2" rims.
Agree that the missing numbers were in the region of 205mm wide.

205?!!?
I reckon it was more like 185 for a HR-HQ steel rim.

I used to be able to easily fit "ER70s" on the wider styled rim available
for Valiants. Styled rims came in (and I could be corrected here) 6" and 7".
I'm certain there were 2 widths however. The rarer wider styled rim, looked
pretty good in the bulbous guards of the "tank-body" Vals. It may be, they
were 5 1/2" and 6 1/2". Which cars Chrysler used the wider styled rim, I;m
not sure. Probably, stock on V8s, and optional for all models?

Jason

[John_H]

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.

Wasn't it merely the designation for one of the infamous "Steel Cat"
series?... Probably one of the most shit awful tyres ever to hold air
(if you were lucky). Which is hardly surprising, since the likes of
Michelin and Pirelli already had a 20 year head start on SA Rubber
Mills when they released the first Australian radial. But I
digress....

It tells you nothing about the size, other than what range of sizes
they may have made them in at the time. Chances are it also told you
very little about the aspect ratio (in spite of the inference) given
the sort of tolerances they were manufactured to.

They also had a grading system... which was well known inside the
industry at the time, but otherwise a reasonably well kept secret.
IIRC there were a series of spots in the moulding, which were
variously ground off depending on the manufacturing tolerances
achieved. Car manufacturers got the ones with all the spots intact...
the aftermarket got the rest (the number of spots depending on who you
bought 'em off).

Them were the days!

[Toby Ponsenby]

Post by John_H

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or
GTS was the ER70. Does anyone here remember them and if so, what is the
equivalent in modern day tyre size? I'm thinking around 205/70x14, but
it might be narrower.

Wasn't it merely the designation for one of the infamous "Steel Cat"
series?... Probably one of the most shit awful tyres ever to hold air
(if you were lucky). Which is hardly surprising, since the likes of
Michelin and Pirelli already had a 20 year head start on SA Rubber Mills
when they released the first Australian radial. But I digress....
It tells you nothing about the size, other than what range of sizes they
may have made them in at the time. Chances are it also told you very
little about the aspect ratio (in spite of the inference) given the sort
of tolerances they were manufactured to.
They also had a grading system... which was well known inside the
industry at the time, but otherwise a reasonably well kept secret. IIRC
there were a series of spots in the moulding, which were variously
ground off depending on the manufacturing tolerances achieved. Car
manufacturers got the ones with all the spots intact... the aftermarket
got the rest (the number of spots depending on who you bought 'em off).
Them were the days!

Yes indeedey.

And Ford USA got it in the neck for wheeling and dealing with a supplier
who turk 'em down - but not until hundreds of their loyal customers
managed to do the same. And hasn't Jac been quiet, too;-)


Given how a tyre is actually made, WTF is the wheel balancing for new
tyres caper about?
An admission that the manufacturing standards are CRAP, is what it is...

[John_H]

Post by Toby Ponsenby

Post by John_H
They also had a grading system... which was well known inside the
industry at the time, but otherwise a reasonably well kept secret. IIRC
there were a series of spots in the moulding, which were variously
ground off depending on the manufacturing tolerances achieved. Car
manufacturers got the ones with all the spots intact... the aftermarket
got the rest (the number of spots depending on who you bought 'em off).
Them were the days!

Yes indeedey.
And Ford USA got it in the neck for wheeling and dealing with a supplier
who turk 'em down - but not until hundreds of their loyal customers
managed to do the same. And hasn't Jac been quiet, too;-)

Different branch of the very same supplier, albeit at a somewhat later
date (who now manufacture under three different brand names here in
Oz).

Post by Toby Ponsenby
Given how a tyre is actually made, WTF is the wheel balancing for new
tyres caper about?

Buy the right brand and you usually don't... standards may have
slipped a bit in recent times though. :)

Post by Toby Ponsenby
An admission that the manufacturing standards are CRAP, is what it is...

[Marts]

John_H wrote...

Post by John_H
Wasn't it merely the designation for one of the infamous "Steel Cat"
series?... Probably one of the most shit awful tyres ever to hold air

Dunno. I seem to recall that Dunlop "Aquajets" were also available as ER70s...

Shit, it's been a hellava long time since then.

As for the Steel Cats, I can still remember Brock's ads for them and a black cat
jumping onto the road or something like that.

[Knobdoodle]

http://www.euroshina.com.ua/en/tyres/Bridgestone/Er70

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.
--
The most effective way to remember your wife's birthday is to forget it once.

[Legoman]

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.

You are correct. E=205

Vintage radial letter load-ratings vs. tyre size.
On some vintage vehicles, notably the Jensen Interceptor, the tyre sizes
were denoted as ER70VR15. The '70' refers to the section height as you
might expect, and the '15' is the wheel dimension, but on first inspection
there appears to be no section width. Actually there is, but it's in yet
another odd format. In this case, the first letter is the thing to look at.
The letter itself has no direct equivalent to modern dimensional sizes but
instead relates to load ratings; the higher the letter the more load it can
carry. With vintage tyres, higher loads translated into bigger tyres, so
the close approximations between old load and new size these days are:
C = 185 D = 195 E = 205 F = 215 G = 225 H = 235 etc.
In this example then, ER70VR15 means 205/70 R15 with a 'V' speed rating.
Frankly that's a little optimistic for something like a Jensen Interceptor,
so if you're looking to replace tyres for this type of vehicle, an 'H'
speed rated tyre is the better choice, and it's cheaper.

From http://www.carbibles.com/tyre_bible.html

[Athol]

Post by Legoman

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.

You are correct. E=205
on first inspection
there appears to be no section width. Actually there is, but it's in yet
another odd format. In this case, the first letter is the thing to look at.
The letter itself has no direct equivalent to modern dimensional sizes but
instead relates to load ratings; the higher the letter the more load it can
carry.

Since load capacity is a function of casing construction and sidewall height
(okay, I admit that that's a gross simplification), and we're talking about
a series of tyres with comparable casing construction, the ER78-14 will have
the same sort of sidewall height with a narrower section width.

Post by Legoman
With vintage tyres, higher loads translated into bigger tyres, so
C = 185 D = 195 E = 205 F = 215 G = 225 H = 235 etc.

I was going to say that that was only correct for 70 series tyres, but
then I looked it up in one of the manuals that I have here, and these
numbers are a little bit too "rounded". For example, C = 194 according
to the book...

Straight from the book, ER78-14 has a width of 188 and a diameter of 655mm,
while ER70-14 has a width of 206mm and a diameter of 652mm. Those numbers
look just about right to me.

[Knobdoodle]

Post by Legoman
You are correct. E=205

I reckon you're stroking your goat!
I have no evidence but I don't believe that 205s would've ever been
"standard" on HQs let alone HRs!!
-
Knob

[Noddy]

Post by Knobdoodle
I reckon you're stroking your goat!
I have no evidence but I don't believe that 205s would've ever been
"standard" on HQs let alone HRs!!

I can't remember what HQ's had, but HR's sure as shit never had anything
like that from the factory.

--
Regards,
Noddy.

[Athol]

Post by Noddy

Post by Knobdoodle
I reckon you're stroking your goat!
I have no evidence but I don't believe that 205s would've ever been
"standard" on HQs let alone HRs!!

I can't remember what HQ's had, but HR's sure as shit never had anything
like that from the factory.

The original wheels on HDs were 4.5Jx13 rims with 6.40x13 4-ply tyres.

HT GTS350 got 6JJx14 rims with "D70H14 4P R tyres". "Alternative tyres
include ER70 and other radials are available on order."

HQ GTS got Canadian 6JKx14 Pontiac Rallye rims with Holden centre caps,
complete with "ER70H14 high performance radials."

Straight from reprints of original brochures...

[Knobdoodle]

Post by Athol

Post by Knobdoodle
I reckon you're stroking your goat!
I have no evidence but I don't believe that 205s would've ever been
"standard" on HQs let alone HRs!!

HQ GTS got Canadian 6JKx14 Pontiac Rallye rims with Holden centre caps,
complete with "ER70H14 high performance radials."
Straight from reprints of original brochures...

But does it actually say that the ER70s were 205 wide?
--
Knob
(where's one of them stickers with the replacement tyre sizes from inside
the door when you need one!!)

[Knobdoodle]

OK; this link DOES agree with you:
http://www.geocities.com/MotorCity/2398/tires/TIRE.HTML
It says that the ER70-14 is equivalent to the 205/70-14 or the 185-14
(80-series)

Now that I think about it none of the HR-HQs that I ever had anything to do
with would've had 70-series tyres so it would've been 185-14s that would've
been the sporty tyres.
You win.
--
Knob

Post by Knobdoodle

Post by Athol

Post by Knobdoodle
I reckon you're stroking your goat!
I have no evidence but I don't believe that 205s would've ever been
"standard" on HQs let alone HRs!!

HQ GTS got Canadian 6JKx14 Pontiac Rallye rims with Holden centre caps,
complete with "ER70H14 high performance radials."
Straight from reprints of original brochures...

But does it actually say that the ER70s were 205 wide?
--
Knob
(where's one of them stickers with the replacement tyre sizes from inside
the door when you need one!!)

[Toby Ponsenby]

http://www.geocities.com/MotorCity/2398/tires/TIRE.HTML It says that the
ER70-14 is equivalent to the 205/70-14 or the 185-14 (80-series)
Now that I think about it none of the HR-HQs that I ever had anything to
do with would've had 70-series tyres so it would've been 185-14s that
would've been the sporty tyres.
You win.

Addendum:
Standard "hoon" tyres for HQ were the monster 185's.
Later, taxi's used that size. Some of them retreads.
Reminds me that I had two deflated/destroyed retreads on a cab in the
same (night) shift.
Changed one, borrowed another.
Fucken things were unsafe at any speed, to coin a phrase. In those merry
times, I'd better 250 MILES on a busy night - there were far fewer
obstacles to efficient travel about then - most of it a reasonably high
speeds. .Alright, very high speeds.
Well, as high as possible given the propensity of pissed customers to
discern they were in a GP or similar and remember enough about it to
complain:-) Just needed to be err...gentle, is all.
Anyhow, took cab to owner and said that's it - no decent 'real' tyres, no
driver.
He called me that day. Four new 185's.
Never had another tyre problem. Owner was sufficiently anal to keep
meticulous records of stuff like tyres.
Six months later, he's got the hide to inform me he's been exceedingly
clever. He's actually saved money by using new tyres on his cabs.
Imbecile.
Dam near smacked the mongrel in the mouth.

[Knobdoodle]

Standard "hoon" tyres for HQ were the monster 185's. (snip)

Yep the quoted HT350 and GTS HQ were hardly "the norm".

Six months later, he's got the hide to inform me he's been exceedingly
clever. He's actually saved money by using new tyres on his cabs.
Imbecile.
Dam near smacked the mongrel in the mouth.

Heh heh; some people are immune to logic!

[Kwyjibo]

Post by Athol

Post by Noddy

Post by Knobdoodle
I reckon you're stroking your goat!
I have no evidence but I don't believe that 205s would've ever been
"standard" on HQs let alone HRs!!

I can't remember what HQ's had, but HR's sure as shit never had anything
like that from the factory.

The original wheels on HDs were 4.5Jx13 rims with 6.40x13 4-ply tyres.
HT GTS350 got 6JJx14 rims with "D70H14 4P R tyres". "Alternative tyres
include ER70 and other radials are available on order."
HQ GTS got Canadian 6JKx14 Pontiac Rallye rims with Holden centre caps,
complete with "ER70H14 high performance radials."
Straight from reprints of original brochures...

Looking at the original brochure at
Loading Image... it
states that the HQ came with D70 tyres as standard.
Loading Image...
indicates that ER70 tyres were available, but I think they were an optional
extra.

[Athol]

Post by Kwyjibo

Post by Athol
HQ GTS got Canadian 6JKx14 Pontiac Rallye rims with Holden centre caps,
complete with "ER70H14 high performance radials."
Straight from reprints of original brochures...

Looking at the original brochure at
http://www.uniquecarsandparts.com.au/brochures/Holden_HQ/Holden_HQ_27.jpg it
states that the HQ came with D70 tyres as standard.

Looking at the real, genuine original 1971 HQ brochure here says that, too.

Conversely, the reprinted 1973 or 1974 brochure says ER70H14.

Post by Kwyjibo
http://www.uniquecarsandparts.com.au/brochures/Holden_HQ/Holden_HQ_29.jpg
indicates that ER70 tyres were available, but I think they were an optional
extra.

As above, the specifications changed during the life of the HQ model. It's
just that back then they didn't call them "series 1", "series 2", etc..

[Legoman]

Post by Athol

Post by Legoman

Post by Marts
Back in the 70s, THE tyre to have on your hot HR or perhaps a HQ SS or GTS was
the ER70. Does anyone here remember them and if so, what is the equivalent in
modern day tyre size? I'm thinking around 205/70x14, but it might be narrower.

You are correct. E=205
on first inspection
there appears to be no section width. Actually there is, but it's in yet
another odd format. In this case, the first letter is the thing to look at.
The letter itself has no direct equivalent to modern dimensional sizes but
instead relates to load ratings; the higher the letter the more load it can
carry.

Since load capacity is a function of casing construction and sidewall height
(okay, I admit that that's a gross simplification), and we're talking about
a series of tyres with comparable casing construction, the ER78-14 will have
the same sort of sidewall height with a narrower section width.

Post by Legoman
With vintage tyres, higher loads translated into bigger tyres, so
C = 185 D = 195 E = 205 F = 215 G = 225 H = 235 etc.

I was going to say that that was only correct for 70 series tyres, but
then I looked it up in one of the manuals that I have here, and these
numbers are a little bit too "rounded". For example, C = 194 according
to the book...
Straight from the book, ER78-14 has a width of 188 and a diameter of 655mm,
while ER70-14 has a width of 206mm and a diameter of 652mm. Those numbers
look just about right to me.

You could have just said "Well done Legoman, thanks for providing the most
concise and best answer while all around you floundered like beached fish.
You're a god. Can I touch you?"

[Athol]

Post by Legoman
You could have just said "Well done Legoman, thanks for providing the most
concise and best answer while all around you floundered like beached fish.
You're a god. Can I touch you?"

LOL.