3 years, 3 MOT passes

[Shahpor]

Hey chaps,

That time of the year once more and old faithful has passed yet again.

Only advisory was for front tyres which I knew about beforehand.

Tester commented on how clean and solid everything underneath looked (I have had the same comment every year) and the emissions barely registered.

Not bad for a car that has managed 137k miles and 10 years of motoring.

Lexus really do know how to build them well.

[J Henderson]

Are the tyres wearing on the inside edge? Or is the advisory just for low tread depth overall?

Anyway congratulations. It's always great to have your car pass with flying colours. Hopefully mine will do the same next month. 

[Shahpor]

Thanks.

It is the outer edge that is wearing out.  He thinks they were underinflated, which could be true because when they were pumped up the steering got lighter.

They are generally worn out anyway.  Between 3 and 4mm tread depth left.  The drivers side outer edge is 3mm and the passengers 2mm.  I asked the guy why that was and he said it was because we have so many roundabouts around here!

I will get a new pair of fronts soon.  There was also an advisory for a nail in one of the rears, but upon closer inspection it hasn't gone all the way through, so no repair required.

[Texas]

Under-inflated tyres normally show wear on both the inside & outside edges of the tread surface, whereas over-inflated tyres will wear along the centre line of the tyre and feedback through the steering will be different in both cases, under-inflated will feel 'heavier' than over -inflated.

under-inflated tyres will have more contact area with the road and therefore MPG will reduce, handling & braking will be affected as there is now a softer than normal link between the car and the road and the chance of a blow out increases as the tyre itself will heat up due to increase in friction and flexing of the sidewall on every rotation!

over inflation gives you less contact with the road so MPG might go up if you survive long enough because your handling and breaking capacities are greatly reduced!!

paul m.

[Linas.P]

Wheres inflation plays it's part, there are much more to it. As mentioned front outsides wears more due to (stupid) mini roundabouts, the inside edges wears on (stupid) speed humps, rear inner edges wear naturally due to the IS250 rear suspension geometry, then different tires needs specific different pressure e.g. from my experience Dunlop Sportmaxx needs higher pressure then standard recommended Lexus, because running standard pressure they develop wear signs of under inflation. And so on... 

One surprising thing about the way IS250 tires wears is that one would expect rear tires to wear quicker on RWD car, but from my experience  (except of the edge wearing issues) it is always front tires which needs changing first, seems like Lexus has over-compensated with wider rear tires.

[Rebecca]

Agree with you there @Linas.P my 250 still had the original Dunlops on the rears at 33k and still had a good 12 months life in them.

However the uniroyal rainsports I had fitted to the fronts at 21k have less tread than the rears.

[Shahpor]

Well, I have managed over 28k on my fronts, so not too bad.  Lots of motorway miles probably helped, but my commute has now changed to 15 miles of twisty single lanes, so I can't imagine the new set will last as long.

I am tempted to try a different brand, but I will probably just stick to the Dunlop SP Sports since I know they are pretty good, even if they are specifically made for a Mercedes!

[Linas.P]

I am about to change my tires as well... amazing mileage from Dunlop Sportmaxx RT.. Fronts are down to 3mm now, but both edges are barely legal, Rears about 4mm, but 3mm inside, technically both still have some life left if not for edges - that is after 42k!

Little bit back to the topic - sadly MOT is hit an miss. Some places are very harsh and checks the cars meticulously, others don't check anything. My car did not have any advisories since 2012 (previous owner) and that was stupid:

Quote

Advisory notice item(s)

• Under-trays fitted obscuring some underside components
• Engine covers fitted obscuring some components in the engine bay

I usually do it at Lexus Woodford straight after service so it is almost 100% to pass, last year I did it in some place near me for many reasons - I held on service until airbag recall parts are in, as well I did terraclean etc. They did everything under 1 hour and it was little bit silly because both before and after Terraclean car showed 0.000 on almost all pollution tests, so they were struggling to prove Terraclean had any effect on my engine  - I was like "are you sure you turned that hydrogen off". But that is not a big surprise it was always showing something like 0.004-0.001 where the limit is like 0.200-0.400 (maybe Lexus has defeat device as well?).

[Guest]

I am about to change my tires as well... amazing mileage from Dunlop Sportmaxx RT.. Fronts are down to 3mm now, but both edges are barely legal, Rears about 4mm, but 3mm inside, technically both still have some life left if not for edges - that is after 42k!

Limit only applies to middle 75 percent. Edges can be worn and still be legal.


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[Linas.P]

Yes, I am aware of that, my point of "still having life left" is not as much legal as I could wear tires to 1.4mm, but more of when I would replace them. I tend to replace tires around 3mm, which my fronts and inner half of rear currently are. That said I probably still going to drive for 1000-2000 miles before replacing as I have few works planned which I want to do before new tires and 4 wheel alignment.

[Shahpor]

It seems I am mistaken and it is my rears that are SP Sports.  The fronts are Sportmaxx RT, like you have Linas.

I just went to have a look (also spent an hour or so cleaning my EGR Valve which was serious choked up!).  You can see the outer edge wear:

 

Strange thing though;  I was looking for replacements and I saw this on Black Circles:

 

Now, mine are the 91 load rated ones, but it seems that for virtually the same price you can have the  RT 2 94's, which they claim has a better fuel consumption rating.  So I can't see any reason not to go for those instead?

As for the MOT itself, those tray and engine cover advisories annoy me.  I know they are meaningless, but it would be nice to have a completely clean MOT certificate, especially as the covers are meant to be there.  I have had my MOT done at the my local Mr Clutch for the last 3 years and they have always been good, with no nonsense cover advisories.  Also, it only costs £24, so I can't see a reason to go anywhere else.

[Tyre Tread]

7 hours ago, Linas.P said:

Yes, I am aware of that, my point of "still having life left" is not as much legal as I could wear tires to 1.4mm, but more of when I would replace them. I tend to replace tires around 3mm, which my fronts and inner half of rear currently are. That said I probably still going to drive for 1000-2000 miles before replacing as I have few works planned which I want to do before new tires and 4 wheel alignment.

Just for clarity minimum tread depth is 1.6mm across 75% of the cebtre of the tread width not 1.4mm.

[Linas.P]

21 hours ago, Shahpor said:

Strange thing though;  I was looking for replacements and I saw this on Black Circles:

That is not strange RT2's are new stock and RT's are legacy and being phased out, so obviously RT2's should be more readily available and cheaper by now especially on the less popular sizes where the stock is probably getting low. As well It is better to go for non-XL ones especially for front. XL has bit harder side walls and give junk ride - not to the level of run-flats but unpleasant.

I am thinking of getting RT2's myself to replace my current RT's...

Yes sorry 1.6, not 1.4mm - anyway by that time it is virtually bald tire so this legal requirement is for blind - any reasonable person would replace the tires well before that for their own and others safety.

[johnatg]

Looking at that tyre wear - I'd certainly get an alignment check. That isn't the sort of wear I'd normally associate with under-inflation or 'too many roundabouts'!

[Linas.P]

What you need to realise as well, this is "typical" wear for Dunlop Sportmaxx RT's - my tires are worn exactly the same. To minimise this effect of "under-inflated wear" on the edges I run tires at a bit higher pressure as well I have alignment done and still have edges going.

Now few thing to note regarding specific design of Dunlop Sportmaxx RT's:

• First of all edges have less thread to begin with - on new tire the central groves are 7 mm and the side groves are only like ~3mm, so even if you have 100% even wear you will have no groves left on outside where the rest of the tire would have ~4mm.
• The next thing to consider is rubber compounds of the tire - Dunlop states they use:

  Quote

  POWER BRAKING BLOCKS

  High stiffness blocks that maintain rigidity when braking force is applied. The increased stiffness helps to ensure optimal road contact when braking at high speeds.Benefits Shorter braking distances, especially at high speeds.

  https://www.dunlop.eu/en_gb/consumer/tires/sport_maxx_rt.SPTMAXXRT.html

  what than means in human language that the blocks of thread on the outside are made from more sticky rubber which promotes braking, however they wear quicker then the rest of tire. On my (worn) tire I can actually see where 2 compounds meets and the outside blocks are made of sort of more porous rubber.

Finally, even if it looks like the tire could have had little bit more life in it if not for the edges - 28k is still great mileage.

[Shahpor]

On ‎12‎/‎03‎/‎2018 at 10:18 AM, Linas.P said:

That is not strange RT2's are new stock and RT's are legacy and being phased out, so obviously RT2's should be more readily available and cheaper by now especially on the less popular sizes where the stock is probably getting low. As well It is better to go for non-XL ones especially for front. XL has bit harder side walls and give junk ride - not to the level of run-flats but unpleasant.

I am thinking of getting RT2's myself to replace my current RT's...

Yes sorry 1.6, not 1.4mm - anyway by that time it is virtually bald tire so this legal requirement is for blind - any reasonable person would replace the tires well before that for their own and others safety.

Sorry, I should have been more specific.

What I meant was the difference between the one of the left (RT 2 91) and the right (RT 2 94).  As you can see, the fuel rating on the 94 rated tyre is much improved while the other stats are the same.  So, since the 94 tyre is only £1.07 more than the 91, I was wondering whether they were worth getting, even with the potentially harsher ride.

[Linas.P]

It is hard to say, that potentially harder ride is what gives the improved fuel economy as well. Like inflating the tires more I guess.

From my experience - you won't notice the difference betwen say A or C rated tires. Maybe some negligible difference between A and G... The point is that on all modern tires the fuel economy is much improved in comparison with say tire 10 years ago + there are so many factors that the difference is hard to tell. E.g. if you leave any tire under-inflated that could make like 5MPG difference, of if alignment is wrong etc. whereas difference in perfect condition between A and G rated tire maybe going to be just 1MPG. Obviously, this is just guesstimate - but I would not have high hopes to save fuel based on tire rating.