Kumho 20" sidewalls cracking.

[captaindarling13]

Hi all,

By way of introduction, I've been a member on here since April 25, I have a 2021 T6.1 T30 Lwb, Redline camper conversion, lowered and on Supermetal 20" wheels.

The tyres, as fitted brand new when I bought it two years ago, are Kumho Ecsta 275/35/20 Y102. On a recent trip to France the sidewall blew out of one of the rears resulting in a split you could fit your hand into. Preparing for another trip, and with this in mind, I have checked the others and they are all cracked, and look to be ready to fail in a similar way. I should add that these tyres have done about 10k miles. I run them at 38psi.

I guess my question is has this happened because the Kumho's are inferior and not suitable for this vehicle, or is it something more sinister in terms of suspension setup/other?

Research on here is pointing me towards Michelin CC3's, but at over £1k for 4 I don't want to have the same issue again.




Thank you in advance for any thoughts on this!

 

[Lubrown]

Have you checked the load rating of the tyres? What number is it on the sidewall?
And do you know the weight of the van when set up how you use it at its most loaded? Public weighbridges don’t charge much at all (I paid a fiver) for this service and you only need to do it once. You can usually find them on your local council website.

Those last pictures look as though the tyre has scuff marks too - kerbing and particularly pothole impacts can damage the sidewalls and you may not always see this externally. Apart from safely avoiding the potholes you can and parking without bumping up kerbs I think the increased likelihood of damage is a pay off of having low profile tyres.

 

[captaindarling13]

Thanks, I should add that the cracks are only on the inside walls. Nothing on the outside at all. The failure was also inside wall.

Other than the Y rating, is there any other load rating to look for?

 

[Pewt]

Is the van a daily or does it sit for quite a long time in between being used ?

 

[captaindarling13]

Sits between holidays. I run it to work now and again. Probably goes 3 weeks or so unused.

 

[DXX]

Research on here is pointing me towards Michelin CC3's, but at over £1k for 4 I don't want to have the same issue again.

That’s a reasonable price for quality tyres, my advice is stop driving the van, I wouldn’t even drive that to the tyre shop. Take a couple of wheels off at a time and transport them for new tyres.

 

[FWhite]

Kumho shouldn't be that bad, by itself, it is kind of big brand in Asia, (had them on a Renault, where just OK), but with that non OEM size, while barely (102) load rated, was the air pressure appropriate?
There will be no official reference...
Possibly you would have to run them close to their max pressure rating to be able to actually carry the rated load and that may have been quite uncomfortable. As usual you may have to compromise.

My (fully personal and unprofessional) take on it:
These are not wheels for a 3t van.
Stay with what is on your VW label/papers and you will be safe.

 

[Lubrown]

Thanks, I should add that the cracks are only on the inside walls. Nothing on the outside at all. The failure was also inside wall.

Other than the Y rating, is there any other load rating to look for?

Yes, there is. So you have the size - 275/35/20 and the speed ‘Y’, there should also be another number nearby - in the nineties or early 100… that is the load rating.
The tyre pressure sticker on your door pillar should give you some clue as to what your van needs (t26 will need less than a t32 etc) but to be safe there is an axle rating sticker under the bonnet - halve that and round up to the next tyre size.

 

[Lubrown]

Other thing to note is somewhere on the sidewall in tiny font will be a maximum cold pressure rating for the tyre.

The tyres on my van, all OE size and spec, have a max rating of 50psi while the sticker on the door pillar suggests (if my van is fully loaded) a max of 51psi. Don’t go over the rating on the tyre though as pressure increases as the tyre gets hot.

 

[captaindarling13]

Ok, yes they're Y102.

 

[FWhite]

Yes, there is. So you have the size - 275/35/20 and the speed ‘Y’, there should also be another number nearby - in the nineties or early 100… that is the load rating.
The tyre pressure sticker on your door pillar should give you some clue as to what your van needs (t26 will need less than a t32 etc) but to be safe there is an axle rating sticker under the bonnet - halve that and round up to the next tyre size.

The OP said already:
<<
The tyres, as fitted brand new when I bought it two years ago, are Kumho Ecsta 275/35/20 Y102.
>>
So, 102 load rating *should* be barely enough for a T30.
While that tyre *may* be legal in the UK (it certainly isn't in most of EU)
the load rating alone tells you nothing about the applicability of that tire to yout T6. Only the OEM or someone with equivalent professional knowledge can decide that. In particular the inflate pressure in your case will be complete guesswork and quite likely the *safe* one will be uncomfortable.
Again, personal unprofessional opinion.

 

[Phil_j89]

Might be worth the replacement, along with a wheel alignment - as the tyres look to be more worn on the outside edge.

You might find that it's a good opportunity to change tyre size, a 275 wide tyre on an 8 / 8.5 wide wheel could cause sidewall issues due to size.

 

[Bav]

So, 102 load rating *should* be barely enough for a T30.

Minimum load rating for a T30 is 101, so 102s are perfectly fine.

 

[Lubrown]

the load rating alone tells you nothing about the applicability of that tire to yout T6

Not true.
If the load rating was say 87 that would instantly tell us it’s not applicable (suitable) for a van.
Stranger things have happened.

 

[DXX]

Those cracks probably took weeks to get to this stage, perhaps get into the habit of more regular inspections.

 

[FWhite]

Not true.
If the load rating was say 87 that would instantly tell us it’s not applicable (suitable) for a van.
Stranger things have happened.

Not entering again on the material subject, you are of course entitled of your opinion, but the last logic you are applying here is "not true".
The fact that the 87 are not suitable do not tell us that the 102 (or 101) are .
That is deduction by negation.
Just saying.

 

[StratosFearXX]

I'd be interested in how old the tyres are? There's a 4 digit date code on them somewhere. I know you say they're 2 years old but worth a look.

DOT WWYY - Week Year.

 

[JumpShip]

Regardless , they look unsafe and I wouldn't be happy to run them .

 

[Lubrown]

Not entering again on the material subject, you are of course entitled of your opinion, but the last logic you are applying here is "not true".
The fact that the 87 are not suitable do not tell us that the 102 (or 101) are .
That is deduction by negation.
Just saying.

I’m more than happy if you block me - so you don’t get triggered when I’m sharing your forum.

Click on my avatar on a post from me, click ignore, have a sigh of relief, a glass of Champagne and a fat cigar.

 

[FWhite]

I’m more than happy if you block me - so you don’t get triggered when I’m sharing your forum.

Click on my avatar on a post from me, click ignore, have a sigh of relief, a glass of Champagne and a fat cigar.

I won't do anything like that. Why should I?
Mine was only a technical - mathematical consideration.
Sorry if I disturbed you or anyone else.