Clueless about tires...

[Terier]

OK, I need it spell out for me.  Before posting here I did check out the library but I am still confused.  I understand the concept but I really need a visual aid.  I couldn't even figure out where I should post this.

My two questions:
What size tires do I have?  Are they 15 inch?
What is the age of the tires?


Thanks!

 

[Ned]

Yes, they are 15" tires.  Can't tell the age without the DOT code.

 

[Terier]

Now I know why it didn't make sense.I will check on the missing dot code tomorrow.    After posting here I went back to the library and found a visual aid.

Would it be any different on auto tires?  I tried reading my truck tire but it doesn't look the same as the visual aid in the PowerPoint.
Dot: M3YU R9MX 1111

A general question - would some of the lettering or numbers refer to the wide of a tire?  Like a fatter tire vs a skinny tire.  My cousin had a blow out on her trailer and the repair guy put a new tire on but it looks wider than the other ones.

PS:  Just came across another thread "Tire code help" which should be helpful to me once I find the dot code.

 

[Water Dog]

The ST refers to a tire manufactured for trailers, the 205 is the width of the tire in millimeters, the 75 is a ratio-it's 75% of the width of the tire - in this case 75% of 205 milimeters will give you the height of the sidewall of the tire. Two side wall measurements (upper & lower) plus the diameter of the rim = the height of the tire. Goes something like this: 205millimeters divided by 25.4 (metric to english) = 8.07 inches (width of tire) X .75 = 6.05" (1 sidewall height) X 2 = 12.1" (2 sidewall heights) + 15" (rim diameter) = 27.1" (Overall tire height)

 

[seilerbird]

Dot: M3YU R9MX 1111

1111

These tires were manufactured during the 11th week of 2011, March 13th to the 19th.

 

[Terier]

1111

These tires were manufactured during the 11th week of 2011, March 13th to the 19th.

Ok, now I understand.  My mind kept going to the 11th month instead of week.

 

[Terier]

The ST refers to a tire manufactured for trailers, the 205 is the width of the tire in millimeters, the 75 is a ratio-it's 75% of the width of the tire - in this case 75% of 205 milimeters will give you the height of the sidewall of the tire. Two side wall measurements (upper & lower) plus the diameter of the rim = the height of the tire. Goes something like this: 205millimeters divided by 25.4 (metric to english) = 8.07 inches (width of tire) X .75 = 6.05" (1 sidewall height) X 2 = 12.1" (2 sidewall heights) + 15" (rim diameter) = 27.1" (Overall tire height)

...so my 15 inch tires are actually more like 27 inches from ground to top of the tire?  The 15 inch is referring to the hole the rim fit into and not from ground to top of tire.

As for metric sytem I guess I should had taken math in high school.  Back when I was a teenager we only needed one semester in math to graduate.  I took that one semester in elmentary math.  (How sad!)  All I have to say is "small math in high school = small numbers on paycheck".  Things have a way of coming back to bite you.

I'm printing this thread out so I can refer to it as needed.  Thanks to everyone for helping me. 

 

[Gary RV_Wizard]

15" is the diameter of the wheel (rim) the rubber tire is mounted on. So yes, the diameter of the tire and wheel together is about 27". Probably a bit less, because the weight of the vehicle compresses the tire on the bottom as it rolls. The more detailed specs for the tire will state its "rolling diamter", but that information is not on the sidewall.

Here is a web page that explains all the stuff that is embossed on the tire sidewall and links to further explanations of each item or term.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=33

 

[Lou Schneider]

As for metric sytem I guess I should had taken math in high school.

Going to Google and typing in "Convert 205 mm to inches" works for me. 

 

[Mavarick]

If you want a handy conversion tool try this one. By far the best I have found and have been using it for years: http://wscope.com/convert.htm
It's free and easy. I downloaded again and scanned it with Norton and Malwarebyte just to be sure it is clean.

 

[Terier]

It was hit and miss checking for data on the trailer tires.  It must be on the inside because I coudn't find it on the outer side.  I was able to take a peek at the spare tire.  Am I reading this correctly:  week 52 in 2009?

Today I also learned that if I scrolled down I can see more listings in the library.  Last night I couldn't understand why tires was not listed.

 

[Lou Schneider]

Yes, that's right Terier.  5209 is the last week (52) in 2009.

If you ever see a 3 digit code, that means the tire was made before 2000.  Same format -two digit week followed by the single digit of the year in the 1990s.

 

[Terier]

You guys been a big help - thanks.

Now I need to verify the DOT on the other 4 tires instead of assuming it's the same as the spare.  It's hard to have it on the side you can't see. 

 

[seilerbird]

Now I need to verify the DOT on the other 4 tires instead of assuming it's the same as the spare. 

Good idea. Assuming is the mother of all foul ups.

 

[Jarlaxle]

Also, some companies use the old alphanumeric system for sizing trailer tires: your ST205/75R15C is equivilant to an F78-R15-C.

I have to say I am surprised to see 15" trailer tires with load range C...most 15's I see are LR D, most C's are 13" or 14".

 

[Terier]

Also, some companies use the old alphanumeric system for sizing trailer tires: your ST205/75R15C is equivilant to an F78-R15-C.

I have to say I am surprised to see 15" trailer tires with load range C...most 15's I see are LR D, most C's are 13" or 14".

Sounds like LR D would be better than LR C tires.  Is the difference in how much weight they can carry?

 

[Jarlaxle]

Yes, a LR D carries more weight than a LR C, but the WHEELS might not be rated for the higher weight and pressure.  Do not overload the wheels!