No Options Apply 17.56.1 On-road tyre replacement help.

[firthy]

Ive searched but can only see ob related tyre replacements.

We have a 2012 17.56.1 dual axle with the GT Radial ST-6000 185R14C 104/102N tyres which are way out of date and I've noticed cracking on the sidewalls. Doing a trip in Jan (if Dan lets us) and dont want to risk it.
My question is on the load rating, do I need to stick with the 104/102 rated ST-6000 tyres as these are pretty specific, or can I fit an easier to source LT tyre like a Hankook 185R14C 102/100R (VANTRA LT RA18 8PR M+S)
Does the drop from 104/102 to 102/100 make a difference legally, is it still in spec?
Pics for reference, thanks..

 

[Drover]

If you look at a LR chart it will show that 102 is 850kg per tyre so thats 1700kg per axle while 104 is 900 and 1800kg per axle, check what the axle load of the van is if your tyres match or exceed that then you are sure to comply............. The N and R ratings are Speed ratings in this instance N is 140kph and R is 170kph so more than enough.

So by the looks should be good and LT is certainly a better van tyre allows more room to play with pressures...

 

[firthy]

Thanks, on the plate it says "Axle group load capacity 2900kg" Does that mean I divide by 2 as its dual axle? eg 1450kg per axle

 

[Drover]

Yes it does, the Hanhook's would be well above the vans ATM being they give you a couple of hundred over the Axle rate............. The LT will negate a bit of side movement as well as mean your not running close to max pressure if using a "P" tyre........... You will have to work out a new tyre pressure for these tyres, start at what the plate says or your usual then check them after an hour or so next run , if the pressure is around the 4-6 psi higher than when cold your pretty well on the money, when the outside temp is 25-30 deg sort of thing...

 

[mikerezny]

Hi,
here is a link to the tyre pressure calculator I use as a starting point for setting the tyre pressure on my van:

http://www.gnschassis.com.au/tyre-pressure-calculator/

The correct tyre pressure depends on the tyre, load on the tyres, and also the road surface.
This is quite well explained on this website.

take care
Mike

 

[Drover]

Easy calculator, think they would give the answer in PSI instead of kpa, their pressure for my van is a bit high for my tyres which I have found the sweet spot to be 48psi not 60 as they say I may be guessing my weight heavier.... but my wheels are big for your normal van which may change the dynamics somewhat..

 

[mikerezny]

Easy calculator, think they would give the answer in PSI instead of kpa, their pressure for my van is a bit high for my tyres which I have found the sweet spot to be 48psi not 60 as they say I may be guessing my weight heavier.... but my wheels are big for your normal van which may change the dynamics somewhat..

Hi @Drover,
as clearly stated, in bold, on that website in the paragraph just above the calculator, one can enter either PSI or kPa, the inflation pressure will be correct and will be in the units entered.

That is the beauty of science and mathematics, oh, and also the advantage one gets by first reading the instructions!
Any unit multiplied by a constant will give an answer in the same unit.
i.e. 50% of 50 PSI will be 25 PSI

Now, 50 PSI = 344.738 kPa (since 1 PSI = 6.89746 kPa)

50% 0f 344.738 kPa = 172.369 kPa

Now, 172.369 kPa = 25 PSI !!!!!

take care
Mike

 

[Drover]

as clearly stated, in bold, on that website in the paragraph just above the calculator, one can enter either PSI or kPa, the inflation pressure will be correct and will be in the units entered.

Interesting that your page shows instructions mine doesn't say any of that, might have thought I know what I'm doing so was a waste of time ......... here's a screenshot of the page I get covering the calc and the bottom about tyre info..... more than happy for someone to point out the instructions. Same on Chrome and Firefox..

I enter the weight in Kg and tyre max pressure in psi and the answer comes in in kpa but unmarked as such ................ is it time for pie ?

 

[mikerezny]

Interesting that your page shows instructions mine doesn't say any of that, might have thought I know what I'm doing so was a waste of time ......... here's a screenshot of the page I get covering the calc and the bottom about tyre info..... more than happy for someone to point out the instructions.

I enter the weight in Kg and tyre max pressure in psi and the answer comes in in kpa but unmarked as such ................ is it time for pie ?



View attachment 67862

Hi @Drover,
the instructions are in the quote to the right of the tyre: (either in kPa or psi)

If you enter the value in kPa, then the calculated tyre inflation pressure value will be in kPa.
If you enter the value in psi, then the calculated tyre inflation pressure value will be in psi.


What are the values you are entering for your calculation?

As an example:
tyre maximum load 900kg,
max tyre inflation pressure 65psi,
load on wheels 1,264kg
number of wheels 2
gives an inflation pressure of 45.64 which will be psi since I entered psi for the maximum tyre inflation pressure.

Now, 65psi for the maximum tyre inflation presure is close enough to 448 kPa.
Using this, I use the same values as above but change only the maximum tyre inflation value from 65 to 448.
The calculator now displays 314.6 which will now be kPa since I entered kPa for the maximum tyre inflation pressure.
314.6 kPa is close enough 45.62psi.

take care
Mike

 

[Drover]

The bit I have have next to the tyre is describing the details on the tyre, I have increased the size of the screenshot above..
but when I enter the data required:
Actual load on wheels: 2500 .......... Max inflation on tyre: 80 ............. Number of wheels: 4 ..................... Tyre load rating: 120

The answer comes out as 416.666 which is kpa ... thats what I was implying nothing denoting kg/psi/kpa and 60 psi is a bit high I thought but if yours is showing instructions then my Adblocker might not be fully shut down on the page.....


Is the maximum tyre load rating are they meaning the actual LR or the weight in kgs, that might be throwing it out throwing in 1400 in the tyre load rating bit gives me 35 psi, so there you go still too low for me the tyre would be running very hot ...............

Post Script: 4 browsers on 3 computers and 2 phones of various brands and I find no instructions as you described....... so maybe new glasses needed but the sarcasm was wasted.

 

[mikerezny]

Hi @Drover,
ok, I see the problem. Yes, the tyre load rating is actually meant to be entered in kg.

take care
Mike

 

[firthy]

Thanks for the help everyone, will grab those LT tyres.

 

[mikerezny]

Thanks for the help everyone, will grab those LT tyres.

Hi @firthy,
just out of curiosity, was the spare the same age, type, and condition as the rest of your tyres?

Are you intending to replace it as well?

take care
Mike

 

[firthy]

It is the same age and type, Ill replace it a bit later, not planning our next trip until a big one in Jan, so still have time. It actually looks fine, cant see any cracks, never been on the van.

 

[Drover]

I tend to extend the age of my spare, its covered looks okay.