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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11240   
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I can't help with the cruise control question but your wheels shouldn't matter as long as they're fitted with appropriately sized tyres. It's the combination of the two that determines whether your speedo will be out or not. Darren
110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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16th May 2020 12:57am |
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| trailbear Member Since: 14 Sep 2016 Location: Scotland Posts: 401
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So if the vehicle were to be fitted with 265/65r18 would that present a problem?
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16th May 2020 7:30am |
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11240
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No, as that tyre is, as near as makes no difference, the same diameter as a stock 235/85 r16. Darren
110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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16th May 2020 8:35am |
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| trailbear Member Since: 14 Sep 2016 Location: Scotland Posts: 401
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Thanks, I appreciate the advice. I have said it before that there is pretty much always somebody
With the right answerđź‘Ť David |
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16th May 2020 8:57am |
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| Martin Site Admin Member Since: 02 Apr 2007 Location: Hook Norton Posts: 6478 
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The cruise system on a Puma is aftermarket and so independent on the gearbox, it effectively emulates the pedal.
With an auto box conversion what you wouldn’t have any more is the safety system where the cruise disengages when the clutch pedal is pressed on a manual box (during gear changes). However as your pedal input doesn’t change during auto box shifts then the aftermarket cruise should work fine. As above, it’s not the wheel size which determines the speedo reading, it’s the tyre circumference/“rolling radius”. Typical 18” tyres used on Defenders are the same circumference as the factory fit 235/85R16 or 750r16 tyres.  1988 90 Td5 NAS soft top
2015 D90 XS SW |
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16th May 2020 9:58am |
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| DAZ110 Member Since: 06 Dec 2007 Location: East Sussex Posts: 2003 
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When I fitted BFG 265/65r18 tyres it made my speedo more accurate.
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16th May 2020 10:01am |
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| trailbear Member Since: 14 Sep 2016 Location: Scotland Posts: 401
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Thanks Gents
That is reassuring that the cruise control will still work, It was something that I hadn’t really Considered when deciding on the conversion. Also glad that the larger wheel choice won’t cause speedo reading problems. |
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16th May 2020 10:18am |
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| BogMonster Member Since: 05 Feb 2008 Location: Stanley Posts: 389  
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Most standard Defender speedos over-read. A number of years ago I used to work with police vehicles and spent a bit of time calibrating different speedos for one reason and another and my recollection is that the law says that a speedo can over-read but not under-read so most manufacturers tend to err on the side of caution and go for a few percent over.
I have never calibrated my Puma speedo but the older Defenders are over by anything up to 10%, which means that fitting slightly larger tyres (which tends to be what people do) simply reduces the error a bit, making it more accurate. If the speedo is calibrated for a standard 32"ish tyre like a 235/85R16, you'd probably have to go to 35" tyres before it would under-read. --- 2006 Defender 110 SW 300Tdi • 2011 Ford Ranger XLT crewcab • 2015 Defender 110 Station Wagon Utility TDCi |
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16th May 2020 4:50pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16857 
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Virtually every vehicle on the road will have a speedometer which over-reads, and there is a very simple reason for this.
Speedometers are by law allowed to over-read by up to 10% but are not allowed to under-read at all. Since it is inherently very difficult to guarantee that a speedometer is spot on (and for 'difficult' read 'expensive') most instruments are designed to be accurate plus or minus 5%, which is relatively easy and inexpensive. However in order for them then to be legal, i.e., to guarantee that it won't end up under-reading, they are actually designed to over-read by 5%. Factor in the +/-5% tolerance and the speed will be 0% under to 10% over, i.e., a speedo at the -5% end of the tolerance band ends still cannot display a lower speed that the vehicle is doing. The design must also allow for all the other factors that can cause inaccuracy, such as tyre wear, pressure and size, so it is perhaps understandable that manufacturers err on the side of caution. |
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16th May 2020 6:32pm |
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| trailbear Member Since: 14 Sep 2016 Location: Scotland Posts: 401
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Gents
Thanks for the information, that’s what I like about the forum, everyday is a school day👍 Regards David |
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16th May 2020 7:34pm |
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| nicks Member Since: 21 Aug 2008 Location: south coast Posts: 469 
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Id like to know how you get on with the auto conversion, as ive been toying with the idea also.
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19th May 2020 3:48pm |
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| trailbear Member Since: 14 Sep 2016 Location: Scotland Posts: 401
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I’ll let you know once it’s done. Certainly haven’t heard or read of anyone having a negative reaction when fitted.
It will be a long trek to Ashcrofts for me but I would much rather go to original designer of the conversion than elsewhere. There will always be those that say it’s not worth it, you’ll never get your money back but for me it’s about choice, I’ve had my other one for 15yrs so I think I can justify the decision. |
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19th May 2020 8:48pm |
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| nicks Member Since: 21 Aug 2008 Location: south coast Posts: 469
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I have the same thoughts as you then, it’s not all about the cost, more the driving experience. I take mine to Provence at least once a year.
How long will Ashcroft have it for? |
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20th May 2020 2:46pm |
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| trailbear Member Since: 14 Sep 2016 Location: Scotland Posts: 401
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Ashcrofts have said that they need the vehicle for between 7 to 10 days to enable them to give it a proper shakedown after fitting and I am more than happy with that.
I agree it is about the driving experience, having only recently been a convert to the automatic transmission driving experience, I wonder why I didn’t consider it sooner. I am amazed the number of people who still say to me that it is a lazy way to drive, well in that case I am lazy and I can live with that👍 |
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20th May 2020 8:22pm |
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