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Larger tyres vs. electronics
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AlexStrugariu
 


Member Since: 20 Oct 2016
Location: Iasi, Romania
Posts: 13

Romania 2005 Discovery 3 TDV6 S Auto Zambezi SilverDiscovery 3
Larger tyres vs. electronics

Hi everyone,

As I would like to get a set of BFG ATs for my Disco in the near future, either for the 17 or 18 inch wheels, I would need to get a different size than stock (e.g. 245 vs 235 for the 17s or 265 vs 255 on the 18s) and these would be 1.7% larger in diameter than the stock ones.

Although I have seen a lot of people (especially in the US or Australia) put larger than stock tyres on their cars, wouldn't this come into conflict with all the vehicle's electronics? I'm guessing the ABS, TR, TC, DSC, HDC should be fine tuned for the standard 30" wheel size and any deviation from this size would affect the functionality of the electronics...

I'm very curious to hear the opinions of more knowledgeable people on this subject.

Thank you in advance for your answers!

Cheers!
 2005 LR Discovery 3 TDV6 S auto
2003 LR Freelander Td4 manual

Land Rover:making mechanics out of drivers since 1948 Very Happy 
 
Post #188041317th Nov 2017 8:41 am
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ronp
 


Member Since: 29 Nov 2006
Location: North Yorkshire
Posts: 15208

United Kingdom 2014 Discovery 4 3.0 SDV6 HSE Auto Corris GreyDiscovery 4

The main consideration re electronics is sidewall height, not the width.
In my opinion a larger/smaller sidewall height of up to +/- 3% won't cause any issues with the electronics.
But that's apart from the readings e.g. speedo, milometer etc, where the different rolling radius would change their accuracy.


That is except if you run tyres of a significant different rolling radius on the same axle.
The vehicle will pick up this difference and certainly in 'auto' will restrict upshift in the top gears.
I'm not sure in 'manual', it may put the vehicle in 'limp mode'.
 🏴󠁧󠁢󠁳󠁣󠁴󠁿  
Post #188042117th Nov 2017 9:19 am
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Erea
 


Member Since: 19 Mar 2012
Location: Munster
Posts: 1509

Ireland 2006 Discovery 3 TDV6 Commercial Manual Zambezi SilverDiscovery 3

Yes the speedometer won’t read the correct speed but it shouldn’t affect any of the others as long as all 4 Tyres are the same size and are pumped correctly. You are not changing by much, but I guess some people would suggest you tell your insurance company just to be safe.
  
Post #188042317th Nov 2017 9:26 am
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L319
 


Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2079

United Kingdom 2005 Discovery 3 TDV6 HSE Auto Buckingham BlueDiscovery 3
Re: Larger tyres vs. electronics

AlexStrugariu wrote:
Hi everyone,

As I would like to get a set of BFG ATs for my Disco in the near future, either for the 17 or 18 inch wheels, I would need to get a different size than stock (e.g. 245 vs 235 for the 17s or 265 vs 255 on the 18s) and these would be 1.7% larger in diameter than the stock ones.Cheers!


You will get that sort of percentage difference between a new and well worn tyre so I don't believe there will be any problem
  
Post #188051817th Nov 2017 1:33 pm
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Discogaz
 


Member Since: 17 Mar 2014
Location: Bracknell
Posts: 1399

United Kingdom 2008 Discovery 3 TDV6 HSE Auto Cairns BlueDiscovery 3

Had 265/65/18's on mine for 40k miles and no issues.
  
Post #188056117th Nov 2017 3:46 pm
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AlexStrugariu
 


Member Since: 20 Oct 2016
Location: Iasi, Romania
Posts: 13

Romania 2005 Discovery 3 TDV6 S Auto Zambezi SilverDiscovery 3

Thank you, everyone, for your replies. I will probably go with the 245 70 r17 BFGs (30.5" vs the stock 30") then.

Someone once told me that I could actually calibrate the car electronically (e.g. with an IID tool) for the increased wheel size. Does anyone here know if it's actually possible?
 2005 LR Discovery 3 TDV6 S auto
2003 LR Freelander Td4 manual

Land Rover:making mechanics out of drivers since 1948 Very Happy 
 
Post #188081618th Nov 2017 11:56 am
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aljo
 


Member Since: 20 May 2007
Location: west sussex
Posts: 804

England 

Yes it can be done with iid 👍👍
 Last night I lay in bed looking up at the stars in the sky and I thought to myself, where,s the f**king ceiling!!
 
 
Post #188082218th Nov 2017 12:33 pm
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df_tom
 


Member Since: 09 Mar 2017
Location: Stuttgart
Posts: 127

Germany 

new 245/70/17 BFG AT2 are 100% speedo equal to gps w/ stock settings of tire size etc. on my my08 TDV6.

No problem at all, and for you in romania the 17" should give you the necessary rubber when you go into the mountains.

Only thing is to remember there is no safety margin in the speedo reading. If it says 100 you go 100. In case of 80 allowed, you will be fined for 20 over.
  
Post #188087918th Nov 2017 2:36 pm
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AlexStrugariu
 


Member Since: 20 Oct 2016
Location: Iasi, Romania
Posts: 13

Romania 2005 Discovery 3 TDV6 S Auto Zambezi SilverDiscovery 3

Thanks again for the info! I was actually suspecting that a slightly larger tyre would actually improve the spedo accuracy. Will definitely go for those then. Don't have an IID tool, but it's on the list.

Cheers!
 2005 LR Discovery 3 TDV6 S auto
2003 LR Freelander Td4 manual

Land Rover:making mechanics out of drivers since 1948 Very Happy 
 
Post #188091318th Nov 2017 4:31 pm
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AlexStrugariu
 


Member Since: 20 Oct 2016
Location: Iasi, Romania
Posts: 13

Romania 2005 Discovery 3 TDV6 S Auto Zambezi SilverDiscovery 3

I also prefer the BFGs because they have the highest load rating of any ATs in these sizes.
 2005 LR Discovery 3 TDV6 S auto
2003 LR Freelander Td4 manual

Land Rover:making mechanics out of drivers since 1948 Very Happy 
 
Post #188091618th Nov 2017 4:39 pm
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