QuestionQUESTION: Hello again,
Sorry I forgot to mention tyre sizes in my previous message.
Tyre size is as follows = 225/75 R16
I have just purchased a set of Goodyear Wrangler Silent Armor LT tyres.
On the sidewall is printed the following.
Load Rating = for single wheel each side at 115 or 1215kg at 80psi.
I normally run 55psi on the rear wheels of my Mitsubishi Triton 4x4 trayback.
Which carries a Slide on camper.
The rear of the vehicle with the camper weighs 1,800kg.
Whilst 1215kg x 2 = 2430kg seems to have ample reserve, what I am not sure is whether I need to run 80psi in the tyres to achieve the maximum load capacity.
Or what is my load capacity at the 55psi that I have in these tyres.
Or what is the pressure I would need to be on the safe side of 1,800kg or perhaps even 2,000kg.
Thank you in advance.
Gabor
ANSWER: Gabor,
The basic principles are:
1) If the tire size is different than what is listed on the vehicle tire placard, then match the load carrying capacity of the original tire size and inflation.
2) The vehicle manufacturer determines what the payload capacity is for that vehicle - and if the loading is within that capacity, then the tire size/pressure combination is adequate.
Unfortunately, Mitsubishi doesn't import a Triton to the US - and the only reference book I have is for vehicles sold in the US. But if your vehicle tire placard says the original tire size was LT225/75R16 at 55 psi, then in order to carry the same load, an LT235/85R16 needs to use 46 psi.
- BUT -
There are a few things that bother me.
In recent years, vehicle manufacturers have been moving towards running tires at 85% of their capacity, based on the tire manufacturer's suggestion - which in turn was a lesson from the Ford / Firestone thing some years before.
An LT225/75R16 at 55 psi has a load carrying capacity of 934 kg and that is NEAR the loading limit - and that is not a good idea. So just based on the loading, I'd recommend you use .... ah ..... 55 psi.
And the last thing I want to point out is that it is important that you look at the vehicle tire placard, because what it says there could change the answer.
---------- FOLLOW-UP ----------
QUESTION: Hello Barry,
Thank you for your response.
The original tyres that were fitted to the vehicle is as follows.
205/80 R16. Tyre placard advises at maximum load to be at 42psi.
Along with advice to say that tyres with lower ratings than 104 should NOT be fitted to this vehicle.
I am however, somewhat confused, with your answer and the PDF data file.
I have downloaded the PDF file with Tyre data information, specifically page 7 showing my size of tyre.
Page 7 data has NO reference to LOAD ratings that are printed on the tyres by the manufacturers.
In view of this along with your answer, do I assume that tyre load ratings on the tyres have NO bearing on the actual load that the tyre can safely carry.
But rather one can only use the data advised as per tyre size along with tyre pressures.
If that is the case what is the use or the point of having load ratings on tyres, other than to confuse owners.
Regards,
Gabor
AnswerGabor,
Since I did not send you a pdf file, it is I who am now confused.
But I am going to take a guess that you are referring to the Goodyear Databook and in it there is a load table. I am also going to guess that you asked other folks the same question you asked me that they (or he) referenced page 7.
I downloaded the Goodyear databook and sure enough, on page 7 there is a load vs inflation pressure table - and yes, it doesn't reference Load Index. That's probably because Load Index is a European thing and up until a few years ago, weren't used by US manufacturers.
But an LT235/85R16 Load Range E will have a Load Index of 120/116 - meaning 120 for single application and 116 for dual.
I hope that clears things up.
