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D4 + Compomotives + BFG 265/65R18 and Speedometer
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Jetlag
 


Member Since: 10 Mar 2012
Location: Johannesburg
Posts: 184

South Africa 2012 Discovery 4 3.0 SDV6 HSE Auto Fuji WhiteDiscovery 4
D4 + Compomotives + BFG 265/65R18 and Speedometer

Hi Guys,

I have ordered Compomotives for my Disco, have also ordered BF Goodrich AT 265/65R18 K02s and I am wondering what effect this will have on the speedometer reading?

I have also ordere an IIDtool Bluetooth version so is there a fix if required?
 Disco 4 SDV6 HSE with Compomotives, BFG 265/65R18s, BigCountry drawer system, Melvill & Moon covers, NL 52L fridge, FR Spare Wheel Carrier, FR Roof Rack, Tenco RTT, FR 50" LED Bar, dual spots, Lift Rods, Mantec Snorkel, C-TEK Dual batt system, 270 Ostrichwing, Maxtrax, Icom ID-5100, Icom ID-51 as secondary, IIDtool BT
Follow my adventures on Instagram @XpeditionAfrica
 
 
Post #18767727th Nov 2017 3:06 pm
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Naks
 


Member Since: 12 Jul 2010
Location: Stellenbosch, Republic of the Western Cape
Posts: 526

South Africa 2011 Discovery 4 3.0 SDV6 SE Auto Fuji WhiteDiscovery 4

I didn't change anything on mine when I put the Compos on, was too lazy to Whistle
 --
2015 Range Rover Sport V8 Supercharged



Defender Puma Workshop Manual: http://1drv.ms/1nNpJeM
Discovery 4 Workshop Manual: http://bit.ly/22l8YHh
Range Rover/Sport L320/L322/L494 Workshop Manual: http://bit.ly/2iH7jgG 
 
Post #18768177th Nov 2017 4:52 pm
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JonM
 


Member Since: 24 May 2012
Location: North Yorkshire
Posts: 1058

United Kingdom 2012 Discovery 4 3.0 SDV6 HSE Auto Santorini BlackDiscovery 4

In the unlikely event that your speedo is accurate now, you'll be going 2% faster than the indicated speed when you have the new tyres on.

However, your speedo probably under reads anyway, so it will probably be less inaccurate with the new tyres than it is now.
 MY2019 D5 HSE 3.0 SDV6 - I've got used to the wonky number plate
MY2012 D4 HSE 3.0 SDV6 - retired to a new home
 
 
Post #18768597th Nov 2017 5:44 pm
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spikekellyrm
 


Member Since: 23 Jul 2015
Location: Manchester
Posts: 637

United Kingdom 2012 Discovery 4 3.0 SDV6 XS Auto Baltic BlueDiscovery 4

I've stuck a little quick reference guide on the vanity mirror flap, I'll take a photo of it when I next get in the car
 D4.5 Facelift, Lazer ST4, Prospeed underbody and rack, IID BT, Compomotive/BFG KO2, Series MFlaps, RAI, Dog Gd+XBB, Alive Tuned, T-Max/YellowTop, RemoteFBH, GlassesMod, WheelWinchMod, Jack Mod, LED Mods, Seized Crank Mod....  
Post #18769597th Nov 2017 9:20 pm
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HarryO
 


Member Since: 06 Apr 2010
Location: Brisbane Australia 🇦🇺
Posts: 24

2015 Discovery 4 3.0 TDV6 Base 7 Seat Auto Fuji WhiteDiscovery 4

Have just put on the exactly the same setup and put up a similar post.

Theoretically your speedo should under read by 5.3% so your actually going faster than you think. Eg Speedo = 110km/h actual speed 115.9 km/h). Not sure is this falls within the speedo accuracy tolerance but in my case my speedo under reads and my 2 speeding fines are evidence😞.

Some threads say you can easily adjust the wheel size with your IID tool - others say that it is not recommended because it’s a “Critical parameter that is part of the CCF health-check.”

Hope someone in the know can give a definitive answer..

Cheers..
 Discovery 4 TDV6
Discovery 3 SE (Sold)
Discovery 2 (Sold)
Defender 110 (Sold)
Series 2 (Chev 4.1 Motor & S2A Gearbox) (Sold)
Toyota Hilux bakkie (Ute) (Broke it) 
 
Post #196855328th Jul 2018 11:19 pm
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indy4x
 


Member Since: 24 Nov 2017
Location: Pontypool
Posts: 89

Wales 2006 Discovery 3 TDV6 SE Auto Zermatt SilverDiscovery 3

Had notice the option in the IID menus to change the wheel size, not that I need to yet

Have been checking my D3 against the roadside speed warning signs and the speedo seems pretty accurate
  
Post #196855429th Jul 2018 12:00 am
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gseum
 


Member Since: 15 Feb 2010
Location: Germany
Posts: 158

Germany 2010 LR4 5.0 V8 HSE Auto Zermatt SilverLR4

Here are the infos for changing speedo on D4:
https://www.gap-diagnostic.com/faq-items/a...tire-tyre/
 Discovery 4/LR4 HSE 5.0 V8 MY2010 // Volvo XC90 II T8 R-Design Passion Red MY2017  
Post #19971691st Nov 2018 8:50 pm
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Ent
 


Member Since: 12 Oct 2007
Location: In the cack
Posts: 6404

Iraq 2011 Discovery 4 3.0 SDV6 XS Auto Fuji WhiteDiscovery 4

I have the same wheel/tyre combo and my speedo is bang on without and tweekinh
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Post #19972062nd Nov 2018 1:12 am
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HarryO
 


Member Since: 06 Apr 2010
Location: Brisbane Australia 🇦🇺
Posts: 24

2015 Discovery 4 3.0 TDV6 Base 7 Seat Auto Fuji WhiteDiscovery 4

In the end I checked my speedo against a phone app, Navman and my wife’s car and agree - speedo is bang on with no changes to anything. No excuse for the fines anymore 😫

Can’t argue with the maths so it make me wonder about the default speedo setting accuracy out of the factory - if that is 5% out then everything calculated from the speedo is 5% out (eg L/100 km)

.
 Discovery 4 TDV6
Discovery 3 SE (Sold)
Discovery 2 (Sold)
Defender 110 (Sold)
Series 2 (Chev 4.1 Motor & S2A Gearbox) (Sold)
Toyota Hilux bakkie (Ute) (Broke it) 
 
Post #19974112nd Nov 2018 11:32 pm
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