Attention: TDR Forum Junkies 
This was sent to us from one of our vendors... . but even though its for larger truck tires... its good reference material... so I thought I'd post the links...
AUGUST VOLUME 2 ISSUE 8 2008
COMMERCIAL FLEET
TIRE DIGEST
Information on a Tire Sidewall (what does it all mean)
The authoritative guide to reducing commercial tire expenditures from
Pressure Systems International,
the manufacturer of the Meritor Tire Inflation System by PSIΤΜ
There are hundreds of tire manufacturers around the world
and combined they make thousands of different tire
brands. Additionally, in the commercial truck tire world,
tires are designed to run on specific wheel positions (steer,
drive, and trailer) in specific service vocations (linehaul,
regional, pickup & delivery, on-off road and others).
There is a lot of information cured into a truck tire sidewall
that gives you valuable information about that specific
tire:
- Tire Manufacturer - Tire Brand
- Tire size - Tire load range
- DOT number - Retread DOT number
- Inflation Pressure - Maximum tire load
- Safety warning - Tire Materials
- Directional Tire - Regroovable
• Tire manufacturer and brand is clearly visible on the
tire sidewall in the largest font letter/numbers on both
sides of the tire.
• Tire sizes are broken down into standard aspect ratio
and low profile. For instance, a 11R22. 5 is a standard aspect
ratio tire. 11 is the nominal tread width measured in
inches. R is for radial, and 22. 5 is the wheel diameter
measured in inches. The aspect ratio by default is about
90 which means that the tire sidewall width is 90% the
width of the tread. In low profile sizes such as the
295/75R22. 5, 295 is the tread width measured in mm's
and 75 is the aspect ratio. In this case the sidewall is a lot
narrower than the standard aspect ratio tire size (90 for
standard; 75 for the low profile). The smaller this number,
the less sidewall area.
• It is important to understand DOT numbers. The Dept.
of Transportation requires a 12 digit number on new tires.
Every new tire manufacturer has been assigned a 2-
letter/number designation which can be found on the DOT
website
(Manufacturers' Information).
Retreaders each have a 3-letter designation preceeded by
the letter R (for retread). An example of new tire DOT
number would be MJ 37 AB3D 1508. MJ is the manufacturer’s
plant code, 37 is the tire size, AB3D is the design
code, and 1508 designates the week and year the tire was
built (15th week of 2008). Retread DOT numbers have
only 7 digits (preceeded by the R for retread) designating
plant code and date of production. If a tire has been retreaded
twice, there will be three numbers on the tire -
the new DOT number and two retread DOT numbers.
This indicates to you how old the tire casing is (or how
many times it has been retreaded).
• The tire load/inflation pressure listed on the tire
sidewall is the highest load capacity that the tire can
handle for a given pressure. Your actual pressures
should be determined by the worst case load scenario
that the tire will see in real life.
• Load range is just a letter designation for the load
carrying capacity of the tire. The higher the letter in
the alphabet... the larger is the load capacity.
• There will always be a mounting/dismounting safety
warning.
• The type of material used in the tire construction
(ie. steel) will be listed with the number of plys.
• Some tires are only designed to run in a single direction;
in that case the tire has an arrow that shows
the direction the tire needs to be mounted. And most
tires say “regroovable” which means that after the tire
is worn, there is additional undertread available if you
are interested in regrooving versus retreading.
Get your tire questions answered by PSI's tire expert at
PSI TIRE DIGEST ASK
Photo used courtesy of Technology & Maintenance Council
AUGUST VOLUME 2 ISSUE 8 2008
COMMERCIAL FLEET
TIRE DIGEST
Information on a Tire Sidewall (what does it all mean)
The authoritative guide to reducing commercial tire expenditures from
Pressure Systems International,
the manufacturer of the Meritor Tire Inflation System by PSIΤΜ
There are hundreds of tire manufacturers around the world
and combined they make thousands of different tire
brands. Additionally, in the commercial truck tire world,
tires are designed to run on specific wheel positions (steer,
drive, and trailer) in specific service vocations (linehaul,
regional, pickup & delivery, on-off road and others).
There is a lot of information cured into a truck tire sidewall
that gives you valuable information about that specific
tire:
- Tire Manufacturer - Tire Brand
- Tire size - Tire load range
- DOT number - Retread DOT number
- Inflation Pressure - Maximum tire load
- Safety warning - Tire Materials
- Directional Tire - Regroovable
• Tire manufacturer and brand is clearly visible on the
tire sidewall in the largest font letter/numbers on both
sides of the tire.
• Tire sizes are broken down into standard aspect ratio
and low profile. For instance, a 11R22. 5 is a standard aspect
ratio tire. 11 is the nominal tread width measured in
inches. R is for radial, and 22. 5 is the wheel diameter
measured in inches. The aspect ratio by default is about
90 which means that the tire sidewall width is 90% the
width of the tread. In low profile sizes such as the
295/75R22. 5, 295 is the tread width measured in mm's
and 75 is the aspect ratio. In this case the sidewall is a lot
narrower than the standard aspect ratio tire size (90 for
standard; 75 for the low profile). The smaller this number,
the less sidewall area.
• It is important to understand DOT numbers. The Dept.
of Transportation requires a 12 digit number on new tires.
Every new tire manufacturer has been assigned a 2-
letter/number designation which can be found on the DOT
website
(Manufacturers' Information).
Retreaders each have a 3-letter designation preceeded by
the letter R (for retread). An example of new tire DOT
number would be MJ 37 AB3D 1508. MJ is the manufacturer’s
plant code, 37 is the tire size, AB3D is the design
code, and 1508 designates the week and year the tire was
built (15th week of 2008). Retread DOT numbers have
only 7 digits (preceeded by the R for retread) designating
plant code and date of production. If a tire has been retreaded
twice, there will be three numbers on the tire -
the new DOT number and two retread DOT numbers.
This indicates to you how old the tire casing is (or how
many times it has been retreaded).
• The tire load/inflation pressure listed on the tire
sidewall is the highest load capacity that the tire can
handle for a given pressure. Your actual pressures
should be determined by the worst case load scenario
that the tire will see in real life.
• Load range is just a letter designation for the load
carrying capacity of the tire. The higher the letter in
the alphabet... the larger is the load capacity.
• There will always be a mounting/dismounting safety
warning.
• The type of material used in the tire construction
(ie. steel) will be listed with the number of plys.
• Some tires are only designed to run in a single direction;
in that case the tire has an arrow that shows
the direction the tire needs to be mounted. And most
tires say “regroovable” which means that after the tire
is worn, there is additional undertread available if you
are interested in regrooving versus retreading.
Get your tire questions answered by PSI's tire expert at
PSI TIRE DIGEST ASK
Photo used courtesy of Technology & Maintenance Council
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