Found this reply from Bosch relating to a problem with ESP that a Santa Fe owner had.  Apparently he had a flat tyre (done 24000km) and replaced it with the spare (new).  The ESP Off indicator came on.  No matter what he did, the ESP Off situation would not right itself until  he replaced it the tyre with the repaired worn tyre.

As it appeared on the Australia4WD Forum

I sent email to Bosch and their reply is below........could be one reason that Hyundai recommend replacing all 4 tyres together with same brand size.

Trevor

We would like to advise:
The ESP will disengage if the wheel speed differential is greater than 6% over an extended period.The reason is that with a wheel speed difference of this magnitude the outcome from an ESP intervention is no longer predictable.Turning on the ESP light to warn the driver of an unstable situation eg flat tyre is considered to be the best safety stategy.


Please do not hesitate to contact us again if we can be of further assistance.

Regards

Bob Tait
Automotive Service Supervisor
Customer Service Representative
Robert Bosch (Australia) Pty Ltd

Bob

[Shambles]

Now that is interesting

But it does go to show that our Korean designer cousins have put lots of thought into safety monitoring.

I presume the Fay spare was a different diameter, maybe a space-saving tyre?

[eye30]

I wonder whether this be the same for the i30 with the space saver?

Anyone had to put their space saver on yet?

[sparki30]

We have our first fault with our i30 in 10 months of ownership, the 'ESP OFF' warning light comes on after about 0.5 miles of driving, we have not changed anything,it was parked up at London Gatwick airport for 2 weeks while we were on holiday, picked it up then light came on, this has happened 3 times today when we have driven the car. Using the ESP switch to turn it off does not work. Any ideas? Looks as if an appointment with the dealer may be in order.

[eye30]

You could try disconnecting the battery for, I think 30 minutes, so it erases the ECU memory.

If that does not reset then a Dealer visit, I think.

[Shambles]

Have you checked the tyre pressures ?

[sparki30]

Have you checked the tyre pressures ?

Tyre pressure sensors not triggered but will check tomorrow.

[Shambles]

Have you checked the tyre pressures ?

Tyre pressure sensors not triggered but will check tomorrow.

Going back to Bob's post above, a subtle differential in the wheel speed due to tyre diameters might just cause the ESP to disengage. I always thought that was a brilliant prognosis and even tho you and I have TPMS, always figured the ESP would detect a dangerous rolling difference as worthy of a warning even tho the tyre may not be below the threshold for TPMS to trigger

[Lakes]

Just like to point out, there is a simple easy way to check each wheel-tyre,rolling distance, put a mark on tyre and mark on ground so the two meet at ground leavel, then roll car forward till the mark on tyre meets ground again, mark the ground were they meet then measure the distance. can do that with each tyre, a low inflated tyre car get hot at speeds and grow in size.

[Lorian]

Regarding different size tyres, I once owned a 2L petrol Vectra. I had a puncture in a front tyre. the fronts were due to be replaced, and low on tread. I put on the brand new spare.

The next day I gave the car a somewhat heavy right foot of acceleration (probably the full 140bhp) and I think it got to second gear before destroying the diff. There were several holes in the casing where teeth had stripped and pinged out.

The morale here is keep them the same size!

[sparki30]

Checked tyre pressures today all were fine, used car twice today light didn't come on. Will have to monitor for a while,may just be a gremlin in the software. Thanks for the replies.

I've had my i30 in once for an intermittant ESP light. They found a loose connection. It has come on again since the service but (and I may be wrong here in my timing) I am pretty sure it hasn't come on since I last put air in the tyres. I check the tyres every couple of months or so and normally they need a bit of a top up. I wonder if this may be the cause of my ESP issue.

I'll be getting them to have a look anyway at the next service.