[AlanHo]

I have finally had enough of the excessively noisy Hankook Optimo K415 225/45/R17 tyres on my 1.6 CDRi Premium car. After much research I decided to get rid of the Hankooks and replace them all with Yokohama AVS DB V550 tyres which get many recommendations on the internet and which a friend has fitted to his Golf and who finds them very quiet compared with his previous Continentals.

They are sitting in my garage awaiting fitting. The reason for the delay is that a friend is coming over this week-end with a professional sound meter to take some reference readings in the i30 with the present tyres at differing speeds on various road surfaces.  I will get the new tyres fitted and he will return to do comparative tests on the same roads/speeds later.

I do not expect the new tyres to be as durable as the Hankooks and may have to be a bit more careful when driving in wet conditions - a price I am willing to bear in return for a quieter cabin.

I will post the results as soon as available.

The Hankooks have done only 4000 miles and are hardly worn - so I will sell them to recoup some of the cost.

[Mike SX]

The results will be very interesting.
An expensive act, but the noise can be very tiring, the various road surface materials in the UK do not help.

[Dazzler]

That's great Allan.. We will await the results of your sound tests with much interest  

I'm sure you've made a sound buying decision  

[AlanHo]

Last week I took some noise levels using a small portable noise meter borrowed from a disk jockey friend. He uses his meter to set up his gear at what he calls gigs. I was surprised at the small difference and inconsistent sound levels it displayed between various road surfaces and looked for further advice. I appreciate that the decibel scale is not linear but was concerned about its accuracy when the instrument recorded a lower sound level when my ears were quite sure the car had become much more noisy.

Another friend is a health and safety inspector and he advised me that the tests were not really valid because a cheap meter designed for setting up music loudspeakers at high volumes is not really suitable - it requires a more accurate meter to provide accurate sound level figures across the noise spectrum.

It's all  a bit double dutch to me but it sounds about right - hence his offer to bring his gear over this week-end to accompany me on a test drive and take accurate decibel levels at various frequencies.

[Surferdude]

Looking forward to the results Alan.
One thing though. I don't think you'll be disappointed witht at model Yoko in the wet. If anything, I think it'll be better. As you say, you may sacrifice a little in the tread life department but well worth it IMO.

[AlanHo]

I have a question - probably a dumb one - but I will ask it nevertheless.

The Yokohama tyres I bought are directional. Presumably this prevents you from swapping the wheels corner to corner. However - what do I do about the spare which theoretically will only be suitable for one side of the car.

Am I being thick - or what?

[rustynutz]

Just means you might have to drive around backwards....

[Surferdude]

I have a question - probably a dumb one - but I will ask it nevertheless.

The Yokohama tyres I bought are directional. Presumably this prevents you from swapping the wheels corner to corner. However - what do I do about the spare which theoretically will only be suitable for one side of the car.

Am I being thick - or what?

Not a silly question Alan. I assume from this you have bought five new tyres.
You fit the spare up for the LHS of the car as the majority of punctures, damage and wear occurs on the curb side. Nails, screws etc tend to gravitate toward the gutter with the road camber and the road edge is more likely to break up than in the middle of the road.

Rotation is a simple "front to rear" on the drivers' side and if you want you can introduce the spare into the mix on the passengers' side. Fit it to the front, front to rear and rear to spare.

If you do have to fit the spare onto the RHS, not really a problem. Just be aware of it but it's far less of an issue than a temporary spare or a steel wheel fitted with mags. Then get the damaged tyre repaired and replace it where it was.

[AlanHo]

Not a silly question Alan. I assume from this you have bought five new tyres.
You fit the spare up for the LHS of the car as the majority of punctures, damage and wear occurs on the curb side. Nails, screws etc tend to gravitate toward the gutter with the road camber and the road edge is more likely to break up than in the middle of the road.

Rotation is a simple "front to rear" on the drivers' side and if you want you can introduce the spare into the mix on the passengers' side. Fit it to the front, front to rear and rear to spare.

If you do have to fit the spare onto the RHS, not really a problem. Just be aware of it but it's far less of an issue than a temporary spare or a steel wheel fitted with mags. Then get the damaged tyre repaired and replace it where it was.

Thanks for that - I will do as you suggest

[AlanHo]

Here is the result of the tyre noise tests. Measurement carried out on the same level sections of road with the clutch depressed to minimise engine noise. Sunny dry days – little wind.

Motorway – 65 mph – old and noisy tarmac
Hankook tyres 75 dB-A and 96 dB-C
Yokohama tyres 73 dB-A and 94 dB-C

Motorway – 65 mph – grooved concrete surface
Hankook Tyres 76 dB-A and 95 dB-C
Yokohama tyres 72 dB-A and 92 dB-C

Motorway – 65 mph – low noise tarmac about 12 months old
Hankook tyres 73 dB-A and 93 dB-C
Yokohama tyres 68 dB-A and 79 dB-C

A class road – 40 mph – grit surface dressed tarmac
Hankook tyres 74 dB-A and 96 dB-C
Yokohama tyres 73 dB-A and 94 dB-C

C weighting decibel figures are for the total sound frequency range.
A weighting covers only the frequency range of normal human hearing.

I am aware of some anomalies in the comparisons – however the figures quoted are the average of 3 identical tests on each section of road. In general the Yokohama tyres are less noisy. On very rough surfaces there seems to be little difference between the tyres – but on smoother surfaces there is a more marked improvement.

What was interesting is that there is a section of the M42 near where I live that has a 1 mile section of concrete road which changes abruptly to tarmac.  As the car moved from concrete to tarmac – or vici versa – my ears told me that there was a sudden and significant change in noise level with both tyres – the concrete being noticeably more noisy. However the decibel meter readings did not confirm this.

Summary

The Yokohama tyres are quieter than the Hankooks on most road surfaces – I can hear the difference on all but very rough side roads and it is confirmed by the decibel meter. However the difference is not as marked as I had hoped for other than on smooth low noise tarmac where the Yokohama tyres, unlike the Hankooks, are really very quiet.

It will be interesting to see what the results are in the wet with the Yokohama tyres. More anon....

[Mike SX]

 Must be disappointing.

[Dazzler]

Must be disappointing.

Sounds like some of the problem is the level of soundproofing in the car .. I suspect at Alan's mature age he wouldn't want to be lifting carpets to add more of that..

But any improvement is worth having.. It was one of several reasons I traded my CRDi on the Hybrid..

[rustynutz]

Could some of the noise be caused by the 17" rims and the resulting lower profile tyres?  :-\

To put the db levels into perspective: a 2db or 3db change is regarded as the smallest discernable increment, while 10db represents a subjective doubling or halving in sound level.

So by this measure the difference here, although measurable, will be as Alan found. Noticable but minimal.

[rustynutz]

Could some of the noise be caused by the 17" rims and the resulting lower profile tyres?  :-\

http://www.caradvice.com.au/282/low-profile-tyres/

[Surferdude]

Could some of the noise be caused by the 17" rims and the resulting lower profile tyres?  :-\

Almost certainly - as your later post confirms. However, in Alan's case he was changing from 17" to 17" so the comparison is a fair one.
I must admit I would have expected bigger improvement too, however in my experience (also with fuel consumption improvement claims), manufacturers are going to make out any POD in their product is worthwhile.
I'm pretty interested in this...........

What was interesting is that there is a section of the M42 near where I live that has a 1 mile section of concrete road which changes abruptly to tarmac.  As the car moved from concrete to tarmac – or vici versa – my ears told me that there was a sudden and significant change in noise level with both tyres – the concrete being noticeably more noisy. However the decibel meter readings did not confirm this.

I have noticed a similar noise on bridge expansion joints. It is particularly noticeable on the Story Bridge in Brisbane but only in the i30 (tyres???) as I didn't have it in my Impreza which had stiffer suspension.
Can't offer an explanation, especially the fact that the decibel meter didn't pick it up.
Anyone else got any ideas?

[AlanHo]

A Sequel
I should have known better. Mt friend and I did the Hankook tests on Saturday morning - I had the tyres changed late saturday afternoon and he came back the following morning (Sunday) to do the noise tests on the Yokohama's. What I failed to do was to check the tyre pressures when the new tyres were fitted. I told the fitter to inflate all tyres to 32 psi and was too trusting.

I noticed this morning when I went out in the car that it felt very hard - I reckon I would have felt it if I had run over an ant. I can only presume that I didn't notice it yesterday because there were two people in the car and I was pre-occupied with the noise tests. I checked the tyre pressure when I got back home this morning - they were all different and in the range 39 to 40.5 psi. They are supposed to be 32 psi.

I have let them down to the correct pressure and the car now feels less bumpy and is quite definitely much quieter. By how much I don't know because I no longer have the decibel meter.

Regarding my comment earlier about the change in noise levels as the car moves from concrete to tarmac or vici-versa - I perhaps need to explain that I am not referring to an instantaneous peak - like running over a joint on a bridge - I mean that there is a noticeable change in noise levels between the two surfaces that is made more obvious because of the sudden change from one type to another. After letting the tyre pressures down this morning I have travelled this section of the motorway and the sudden change in noise level is still very obvious.

I will now try to sell the hardly worn Hankooks. If I can't get a decent price for them I shall retain them as spares for when I need new tyres , which I guess will be in 3 years time.  Being then much older I have no doubt my hearing loss will be worse and the extra noise will be less noticeable. If I do this are there any special requirements for storing tyres for 3 years or more?

[Dazzler]

Thanks Alan.. all very enlightening.. Nice to see an Ace amongst the Jokers 

[rustynutz]

What I failed to do was to check the tyre pressures when the new tyres were fitted. I told the fitter to inflate all tyres to 32 psi and was too trusting.

Off topic a bit, but I was thinkin'...if you're running your tyres with 32psi, perhaps this is why your fuel economy is suffering a little?...... :-\

I'm running 40psi all round and have been getting great economy and more precise handling to boot. 

[AlanHo]

What I failed to do was to check the tyre pressures when the new tyres were fitted. I told the fitter to inflate all tyres to 32 psi and was too trusting.

Off topic a bit, but I was thinkin'...if you're running your tyres with 32psi, perhaps this is why your fuel economy is suffering a little?...... :-\

I'm running 40psi all round and have been getting great economy and more precise handling to boot. 

The new tyres had a self adhesive plastic label about 18" long stuck to the tread - they were the full width of the tyre. When the tyre fitter pulled the labels off - a lot of the white adhesive was left behid on the tread surface.

This morning when I checked the tyre pressures I noticed that the adhesive was still left on the tyre shoulders but was worn off at the centre of the tyre - about a third of the tyre width.  This indicates to me that when you put 40 psi into the 17" tyres - only the middle third of the tyre is making proper contact with the road. Hence I will put up with a slightly reduced MPG in return for a better tyre footprint and safety. If Hyundai suggest 32 psi - that is good enough for me.

So far a handling is concerned - I am of an age where comfort and safety are my prime concerns. Long gone are the days when I took bends on two wheels and a door handle.

[eye30]

I'm running 40psi all round and have been getting great economy and more precise handling to boot. 

I'm told by a person in the know that when a car is involved in an accident the crash investigtor will check tyre pressure, assuming tyre(s) are still inflated.

If they differ by more than a certain % from the manufacturers psi then that driver could be held partly to blame or even fully liable for the accident even if he is the innocent party.

Anyone else have views on this?

[eye30]

Regarding my comment earlier about the change in noise levels as the car moves from concrete to tarmac or vici-versa - I perhaps need to explain that I am not referring to an instantaneous peak - like running over a joint on a bridge - I mean that there is a noticeable change in noise levels between the two surfaces that is made more obvious because of the sudden change from one type to another.

I agree with you on this point. 
I sometimes travel on a road which surface is concrete and yes there is an increase in noise.

[Lorian]

I think the issue is the sound has a higher frequency. On concrete.

Sent from my Blade

[Dazzler]

I'm told by a person in the know that when a car is involved in an accident the crash investigtor will check tyre pressure, assuming tyre(s) are still inflated.
If they differ by more than a certain % from the manufacturers psi then that driver could be held partly to blame or even fully liable for the accident even if he is the innocent party.
Anyone else have views on this?

I have heard this too.. I personally believe 34 PSI all around in most cars (which is less than 10% above the recommended) is a good compromise for Ride, handling, economy and tyre wear.. I'm sure accident investigators wouldn't consider that excessive (I guess under 28 or over 40 might be or if say one tyre was more than 5 or 6 PSI above or below the others ... but would depend on the circumstances of the accident. These things are partly scientific amd partly related to what a reasonable person would consider unacceptable)

[rustynutz]

Interestingly when I did a Defensive Drivers Course a few weeks back part of the course was on the importance of correctly inflated tyres.  They recommended tyre pressures of 36psi around town etc, and 40psi out on the highway..... :-\

[rustynutz]

So far a handling is concerned - I am of an age where comfort and safety are my prime concerns. Long gone are the days when I took bends on two wheels and a door handle.

Trouble is, comfort and safety don't necessarily go hand in hand. The tyre pressures Hyundai quote are a compromise, these pressures aren't the optimum for good handling....If you're wanting maximum safety you'd probably want a bit more air in your tyres.....

[Surferdude]

We've had discussions about tyre pressures before on here.
Regarding the insurance angle, I can't speak for the UK or Europe but in Oz any accident investigator is looking for causes of an accident. If one tyre was markedly higher or lowere than the others, I imagine th einvestigatore would be noting it as a probablr contributing factor.
As long as the tyres are inflated to a figure not above the Load Index maximum, I can't imagine there would be an issue.
Alan, thanks for the update on the pressure issue. Rusty is quite right. There is a compromise between rise comfort and handling/ wear.
At the pressure Hyundai recommend you shouldn't have any problems but the tyres will not grip as well in an emergency where swerving is required (or heavy braking for that matter). It's not all about driving quickly, more about being in the best possible mechanical condition for any emergency you face.
I wouls suggest that 36 all round will give you a good compromise - dependable and predictable handling, optimum wear and not too noisy.
But, your call. at the end of the day, you have to be happy with it.
Enjoy your new tyres.
Oh. And storage - preferably on their sidewalls. 4 high is OK but if you have the space, two high would be better and don't store anything on top of them. And keep them away from oils, greases and fumes. In three years' time they will be getting towards the end of their warranty period (5 or 6 years). So just be aware of that and that they'll be a bit harder in the rubber compund, thus providing less grip.

[ithurtydeesl]

Tyre pressures will vary for all cars and tyre types ,an easy way to get the correct pressure for your car is to start at a pressure, say 32 psi cold , then drive for an hour,  then check the tyre pressure again.

 The tyre pressure should rise by 4psi when hot, so if your tyre isn't at 36 psi after an hour adjust your starting pressure by the amount it's either over or under 36 psi.

What if you did this test and found that 30psi produced the "correct" result? 30psi by most measures is borderline "flat".

I've never tried this method but have heard of it but who decided that a rise of 4^c is the optimum? What if a rise of 3^c or even 2^c was better because it resulted in harder tyres? I guess the answer would be that 30psi couldn't give the correct result.

I pump my tyres to a point where I reckon they are working well and monitor the tread wear. I'd be happier to see slightly greater centre wear than see shoulder scrub/wear.

My starting point with any car is 38psi in the front and a couple less in the rear unless I'm packed with rear seat passegers and gear, in which case I pump the rear the same as the front.

The lower the profile the harder I pump. I think this all fits conventional wisdom.

32psi IMO is too soft unless you are certain you won't need to do any emergency braking. 

[beerman]

I set at about 38psi. I did a fairly extensive driver training course and they pumped them up beyond 40 cant remember if it was 42 or 44. Cars got smashed and the tyres went well. Not brilliantly comfortable, but not bad either.

I have both the i30, the wifes Falcon and my Falcon before that at 38 and have found that to be a good pressure. Also gives me a good buffer if there is slackness on checking the tyres (and I'm looking at the wife here!!)