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Discussion Starter · #1 ·
All,




I'm so happy after changing mystock225/40/18 92WRun_YourCarAndYourBackSpineDead
_Flat to a normal Premium Performance tyres <?: prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><O:p></O:p>
<O:p></O:p>
Achieved/Pros:<O:p></O:p>
-MPG in heavy trafficimmediately went from bottom 38 to a very stable 47... Normal daily London driving from 44 to 54! Soon I will test A/B roads and Motorways but already expecting jumps in MPG.
<O:p></O:p>
- Road Noise dropped significantly; dry driving comfort is so much better with wet grip improved like day and night.<O:p></O:p>
- Majority of punctures could be repaired for about £18 at any garage. <O:p></O:p>
- No insurance premiums increased, as long as insurer is notified. <O:p></O:p>
Cons: <O:p></O:p>
- Need to get repairing kit or space-saver wheel in case going too far away from home.<O:p></O:p>
- £495 invested will only be paid back on gains of MPG within 2 years or less depending on the millage.
I went fornew 2013 Goodyear's EfficientGrip Performance tyres (Euro rated: Wet performance A, Economy: B) with less visible rim protectors and same 225/40/18 92W characteristics for safety.
<O:p></O:p>
Edited by: GodsMate
 

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I hate Run Flat Tyres!!!!


Thankfully, I dont have them on my A Class
 

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Wow! That's very interesting feedback there - thanks.

I'm not unhappy with my run-flats but will more than likely change them to 'normal' tyres when I've had a bit of use from them.

Then it will be like having a new car all over again by the sound of it!
 

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Nice, it's a change I'm going to make next year when the tyres have had some wear.

When I made the change on my BMW my insurance did charge me extra on the back of a safety test Evo magazine carried out, so it's always best to check with them first.
 

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anyone know why there is a such a marked difference in MPG - interested as live in London as well and have ordered the night package which comes with run flats
- assume it's the hardness of the rubber ?
 

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I would assume the MPG is due to the extra unsprung and rolling weight of the tyre? I will probably get my full usage out of the run-flats and change them then. It is a pain the cars with the night package come with them but I can understand why they do it.

Edited by: iopean
 

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That's Epic!

Want to change mine too....think I will get some wear in first.
 

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iopean said:
I would assume the MPG is due to the extra unsprung and rolling weight of the tyre? I will probably get my full usage out of the run-flats and change them then. It is a pain the cars with the night package come with them but I can understand why they do it.


so why would they do it - if it has that much effect on MPG would have thought it would have been left to personal choice - or do they assume it is safer to have a run flat then no need to change a wheel at night ????
 

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This is all excellent info & interesting ! The run flat issue was always a concern on the spec list, and so many new cars are going down this route these days, but we all know that they are noisier & poor wearing compared with a regular tyre, however I am very surprised at the MPG difference.....I will definitely be changing mine early !SO......has anyone any info on space savers ? If the hub/wheel nut configuration is correct there may be one out there that would get you out of trouble in an emergency & fit in the back of the car !!??
 

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my delivery isn't due till 13th May so think a call to the dealer to see if I can arrange fitment of normal rather than run flats and what the cost will be - suppose I would also need either a foam kit or space saver as well

Edited by: TerryA213
 

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What correct tyre pressure are people putting into the 18 inch run flats? Also when you change air pressure are you meant to do anything to let the vehicle know its been changed?
 

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TerryA213 said:
so why would they do it - if it has that much effect on MPG would have thought it would have been left to personal choice - or do they assume it is safer to have a run flat then no need to change a wheel at night ????
Cost - It is cheaper to put on runflats than it is to supply a spare wheel with a tyre and the equipment to change it.
 

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I don't have run flats , GregUK, but the tyre pressure warning came up and I had to reset them. The correct pressures are on the inside of the petrol flap! I think any change will register? There will be someone on this forum who will be able to tell you exactly! Edited by: Lynne
 

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Discussion Starter · #14 ·
The tyre pressure was left exactly the same, 250kPa (36psi) / 220kPa (32psi),

This car has no sensors which can register pressure being too low or too high, instead Merc's electronics sensing the wheels behaviour change and only under normal driving condition with no sudden acceleration or breaking, so if your car has flat tyre it will not warn you before you moved off but it will alarm almost immediately when you start driving or if punctured during your trip.

All this and more info on how to teach your car to take on new tyres, and reset flat tyre alarm - see your user manual.

Edited by: GodsMate
 

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Discussion Starter · #15 ·
Front 250 kPa = 2.5 Bar = 36 psi (you / your missis and your car)
Rear 220 kPa = 2.2 Bar = 32 psi (you / your missis and your car)

Front and Rear 270kPa = 2.7 Bar = 39 psi ( 5 passangers and some luggage)
 

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- anymore for anymore
 

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Lynne said:
I don't have run flats , GregUK, but the tyre pressure warning came up and I had to reset them. The correct pressures are on the inside of the petrol flap! I think any change will register? There will be someone on this forum who will be able to tell you exactly!

The way deflation sensors work is the rotational speed of wheels on the same axle, if the speed difference is prolonged then it indicates a tyre deflating. this is how the BMW system works so Iwouldimagine that MB would employ the same technology unless someone can tell me otherwise :)
 

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Discussion Starter · #19 ·
Just a quick update

Previous average A/B/Motorway and local traffic trip was 53MPG which was not bad.
New tyres A/B roads with some local traffic and M25 trip of 62 miles reported


65.6 MPG</font>




Edited by: GodsMate
 
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