hope springs Posted January 19, 2008 Share Posted January 19, 2008 Hi can someone tell me what will happen to the spedo reading on a 1993 Defender 200 TDi 90, which has had new wheels and tyres fitted- 265/65x16, will the reading be higher or lower. I have read various threads on various forums and it appears that every thread gives the opposite info to the last one, so I am a little confused(this seems to be a permanent state at present, must be part of the joys of 90 ownwership) , so any help will be much appreciated. Hope Springs. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 19, 2008 Share Posted January 19, 2008 If you fit bigger tyres than original the speedo will read slow - you're going further for each revolution of the wheel If you fit smaller tyres than original the speedo will read fast - you're going less far for each revolution of the wheel Obviously this is only with regard to overal diameter, width has no part to play and you could change both rim(16" to 15" say) and tyre size, causing more or less of a difference. With regards to being 'correct', you really need to test the speedo against a GPS, My speedo reads more correctly on 255/85R16 than it did on the 205/80R16 it left the factory on. Quote Link to comment Share on other sites More sharing options...
western Posted January 19, 2008 Share Posted January 19, 2008 this might help if you need to change the speedo drive in the transfer box colour/teeth code for speedo drive gears Quote Link to comment Share on other sites More sharing options...
paintman Posted January 19, 2008 Share Posted January 19, 2008 http://www.carbibles.com/tyre_bible_pg2.html scroll about quarter of the way down for a calculator. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 19, 2008 Share Posted January 19, 2008 http://www.carbibles.com/tyre_bible_pg2.html scroll about quarter of the way down for a calculator. Doesn't beat a GPS, the LR speedo isn't that accurate in the first place. Quote Link to comment Share on other sites More sharing options...
western Posted January 19, 2008 Share Posted January 19, 2008 Doesn't beat a GPS, the LR speedo isn't that accurate in the first place. mine must be a good 'un then, it's almost the same as my gps Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted January 19, 2008 Share Posted January 19, 2008 mine's not too bad, 2 or 3 mph difference, with the wrong speedo gear in! Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted January 19, 2008 Share Posted January 19, 2008 Mine is spot on with 255/85s, green 21 tooth drive and TD5 speedo No skill, pure luck Mo Quote Link to comment Share on other sites More sharing options...
jimmy_neutron Posted January 20, 2008 Share Posted January 20, 2008 As said ... bigger the overall diameter of the wheel/tyre, the slower the needle reads for the same speed. Unfortunately this isn't a good excuse for speeding tickets either Quote Link to comment Share on other sites More sharing options...
A Twig Posted January 20, 2008 Share Posted January 20, 2008 Given I lost my licence once for speeding, I've left my speedo reading slightly fast, bu about 5-7 mph. Although it is a bit depressing when Im flat out, and my speedo says 80, and my GPS is saying just about clearing 70 lol... Quote Link to comment Share on other sites More sharing options...
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