QuestionQUESTION: I have 8 Mission TC-108 tires, 225/75 R15 load range D on trailers. On the sidewall it states a max. pressure of 65psi. What is the minimal pressure I can use? Thank You!
ANSWER: Ron,
Load carrying capacity is all about tire size and inflation pressure. So when someone asks me what the proper inflation pressure is, I tell them to look for the vehicle tire placard. And when someone asks me what the maximum inflation pressure is, I point to the sidewall, then tell them that they should use what the vehicle tire placard says.
So I'm wondering, why would anyone be concerned about the minimum? You want enough to hold up the vehicle, plus some extra for safety - and all that would be dependent on what load is being carrying.
So what's going on? Why word the question that way?
---------- FOLLOW-UP ----------
QUESTION: Barry,
Thanks for the quick response. The above named trailers are work related. They are rarely used. Over time they`ll loose pressure. At what pressure below 65 do I need to add air? What is the acceptable minimal pressure that I can use the trailers?
Again, Thanks for your help.
AnswerRon,
OK, now I understand.
As I said above, load carrying capacity is all about tire size and inflation pressure. Without knowing the actual load on the tires we can only take an educated guess as to what the minimum pressure should be - and we want that to be conservative in order to prevent tire failures.
My experience is that trailer manufacturers typically underestimate how much people put in their trailers, so the tires are marginal at best - and for this case it means that 65 psi should be the minimum.
I'd recommend you inflate the tires to 70 psi, and when they drop to 65, then readjust.
But there is another issue you need to be aware of.
Recent bulletins from the tire industry indicate that tires degrade simply due to time. The age of a tire is important even if the tire is unused. There some disagreement over how to best express this age limitation, but my take is:
If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years. If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years. States in between are ..... ah ........ in between.
Here's how to tell how old the tires are:
First locate the letters "DOT" on the sidewall of the tire. Nearby will be the DOT code. DOT codes are 10 to 12 digits long. BTW the digits can be numbers or letters.
The first 2 digits are a code for the manufacturing plant.
The next 2 digits are a code for the tire size.
The next 3 or 4 digits are a code for the type of tire.
The last 3 or 4 digits are the date code. The format is week/week/year/year or week/week/year. These are always numbers.
Starting in the year 2000, the date coding used was 4 digits. That means the largest number you should see for the year is 09. Before 1999 the format was 3 digits. 1999 and 2000 are transition years, so you will find both 3 and 4 digits.
The date code only has to be on one side – and it is permissible for there to be a partial DOT code, so long as one side has the complete code.
