Usually, tire markings are something like "235/85 R 16", which shows width, aspect ratio and diameter. But recently I came across tire that had the following on its side: "7.50 R16 S"
What exactly is "7.50"? Is it a different standard for tyre markings? How does it translate to normal "width/aspect ratio" one?
Thank you
It's an imperial description code, 7.50 being standard on 109/110 LRs until sometime around 1994 or so, 6.50 on 88" and (confusingly)
205 (mm) on 90's - all being x.xx x 16 - the 16 is the rim size.7.50's are genarally the same size, but as there is no aspect ratio they can vary quite a lot - CAMAC 7.50's are 2" taller than eveyone else's!
7.50's are getting quite hard to find these days, but Avon Rangemasters, General and a few others still do them.Richard
There's two systems, and the 7.50 is a measurement in the old system. Essentially, it's the rim width and there isn't any significant variation is aspect ratio. It's in inches rather than mm, and is a different measurement. Most tyre catalogues (or tire catalogs) have some chart of size comparisons. It also has something to do with whether the tyre needs an inner tube.
As usual, if I've got that wrong, a myriad of detailed corrections will be posted presently.
The 7.50 is inches for the width of the tyre there is no aspect ratio so as Richard says they can vary in overall height, and the 16 is inches for the wheel diameter. I believe the S at the end is a reference to the material of the tyre, some military tyres were not rubber but a synthetic material hence S .
Rich wrote: >
The 'S' is a maximum speed rating, IIRC 180kph.
Speed Rating Miles/Hour Kilometers/Hour N 87 140 P 93 150 Q 99 160 R 106 170 S 112 180 T 118 190
U 124 200 H 130 210 V 149 240 Z 150+ 240+ W 168 270 Y 186 300
I love implication! ^^^^^^^^^^^ ||||||||||| Richard
Goodyear also do them, I recently fitted a set of Goodyear Wrangler AT's to my 109 and am quite happy with them. Greg
Thank you for the reply guys. This is very informative
One more question: if vehicle 7.50 tyres, do I have to continue using them? Or May be i can replace them with regular ones of similar size? Does it mean that i have to measure my tires manually and calculate aspect ratio myself?
Because 7.5 inches is about 19cm, then the tyre i should be looking for will be something like "190/? R 16" - do these even exist?
Thank you
In straight mathematical terms you're looking for 195/100R16 which is likely to be nigh on impossible to find, hence the availability of
750R16 radials. If you want to move to mm sized tyres the usual replacement is 235/85R16.
Do rims built to take 750's take the extra width of 235's without problems, or is a rim transplant also called for? I'm thinking standard SIII rims here but may well apply to others too.
Steve
LWB Series rims are 5.5" wide which is really 1/2" narrow for this tyre, however 110 rims are 6" wide and are fine (tyre chart here shows 6.0 -
7.5" rim widths for 235/85R16).90/110 rims went to 6" from TA792789, which is 2000 model year. Until then they shared the Series 5.5" LWB rims (tubed), except for 1-Ton rims which are 6.5" (for 900x16 tyres). Wolf rims are 6.5", available either tubed or tubeless according to taste. Then there's a trillion different types of alloy wheels...............
Richard
No it's not the rim width, that's usually 5.5" for 7.50's, it's the nominal tyre width in inches, this site has a lot of useful info:
Rim width in inches i believe.
On or around Thu, 4 Jan 2007 11:25:20 -0000, "Steve" enlightened us thusly:
according to the charts, no. in practice, I've had 235/85 on 5.5" rims with no trouble, as have thousands of others.
The discos have 7" rims and 205R16 tyres look undersized on 'em.
On or around Thu, 04 Jan 2007 10:02:21 GMT, "Rich" enlightened us thusly:
Old fashioned cross-plies are an assumed 100% aspect ratio, so the nominal width and the nominal height of the tyre are both 7.5"
7.50R16 is something of an oddity in that normally, radial tyres in the UK are given metric sizes, it's basically a radial tyre which is the same nominal size as a 7.50x16 crossply.in America, they have a different system which leads to a size which looks like 31x10.5R15 for example. This is a nominal size of 31" diameter, 10.5" width and is a radial tyre for a 15" rim.
On or around Thu, 4 Jan 2007 13:38:58 -0000, "Nige" enlightened us thusly:
tyre.
No, tyre width, rims are usually 5.5" wide for this tyre. Greg
Coat donned & off i go!
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