dodeer Posted April 8, 2012 Report Share Posted April 8, 2012 Can i use 235 70 r16 on the front and 205 80 r16 on the back of a Discovery just for a couple of days or will it end up breaking the diff? Quote Link to comment Share on other sites More sharing options...
Dr_evil Posted April 8, 2012 Report Share Posted April 8, 2012 check the rolling radius differences, if its only a couple of cm you should be fine for a few days but if its more then I wouldn't bother. It'll put strain on your transfer box and central diff. I ran 240/75's and 245/75's for a couple of days before I changed over to all 245's but they're fairly similar in size, two inches difference in size so a one inch lift from them Quote Link to comment Share on other sites More sharing options...
dodeer Posted April 8, 2012 Author Report Share Posted April 8, 2012 Do you know the original size of Disco 1 tyres? Quote Link to comment Share on other sites More sharing options...
Dr_evil Posted April 8, 2012 Report Share Posted April 8, 2012 Depends on the year originals were 205R16's but the 235/75 is also an option on the later D1's Quote Link to comment Share on other sites More sharing options...
lumpy Posted April 8, 2012 Report Share Posted April 8, 2012 The width of the tyre wont affect the gearing in any way however the profile height will, if you intend to use 4 wheel drive then the profile height should be the same as you will create different gear raitio's Quote Link to comment Share on other sites More sharing options...
Dr_evil Posted April 8, 2012 Report Share Posted April 8, 2012 The width of the tyre wont affect the gearing in any way however the profile height will, if you intend to use 4 wheel drive then the profile height should be the same as you will create different gear raitio's all discos are permanent 4x4…..all the diff lock does is engage the central diff so the power is always split 50/50, diff lock should never been engaged on road anyway unless covered in snow or something to give some slip if not you'll end up winding the gears which leads to snapping of shafts etc as I said, check the rolling rad differences online….a few cm will be fine for a couple of days on road driving Quote Link to comment Share on other sites More sharing options...
lumpy Posted April 8, 2012 Report Share Posted April 8, 2012 all discos are permanent 4x4…..all the diff lock does is engage the central diff so the power is always split 50/50, diff lock should never been engaged on road anyway unless covered in snow or something to give some slip if not you'll end up winding the gears which leads to snapping of shafts etc as I said, check the rolling rad differences online….a few cm will be fine for a couple of days on road driving Calm down cockle !! in your first post the profile height's you stated were the same, i never said you were wrong !! the way to work out a rolling radius is to multiply the radius x 3.142 that will give you the true circumference. Quote Link to comment Share on other sites More sharing options...
lumpy Posted April 8, 2012 Report Share Posted April 8, 2012 check the rolling radius differences, if its only a couple of cm you should be fine for a few days but if its more then I wouldn't bother. It'll put strain on your transfer box and central diff. I ran 240/75's and 245/75's for a couple of days before I changed over to all 245's but they're fairly similar in size, two inches difference in size so a one inch lift from them The only thing changed here is the tyre width (note: profile height's stated are exactly the same) there would be nothing to affect the torque balance between the axel's Quote Link to comment Share on other sites More sharing options...
PhilR Posted April 8, 2012 Report Share Posted April 8, 2012 You can use the calculator here to see what the differences are between one and the other http://www.kouki.co.uk/utilities/visual-tyre-size-calculator Quote Link to comment Share on other sites More sharing options...
Dr_evil Posted April 8, 2012 Report Share Posted April 8, 2012 Calm down cockle !! in your first post the profile height's you stated were the same, i never said you were wrong !! the way to work out a rolling radius is to multiply the radius x 3.142 that will give you the true circumference. The only thing changed here is the tyre width (note: profile height's stated are exactly the same) there would be nothing to affect the torque balance between the axel's Sorry wasn't having a go mate was just explaining the disco t'fer box/diff lock I wasnt on about mine though I was on about his but I couldn't be bothered doing the maths and I actually typed mine out wrong anyway my old BFG's were 245/70s I knew there was a two inch overall difference though which is why I stated that part so one inch rolling radius dif between mine as the new Maxxis tyres were the 247/75s so kinda my fault there to. But yeah if he does the maths and finds a larger difference than one inch in the rolling rad I wouldn't be wanting to run them for more than the trip to and from the tyre shop, my current tyres are huge compared to the old 205's though Quote Link to comment Share on other sites More sharing options...
Vermincinerator Posted April 9, 2012 Report Share Posted April 9, 2012 If you do the sums you will see that there is les then a mm in rolling radius so there will be no effect on diffs etc. Ian. Quote Link to comment Share on other sites More sharing options...
Dr_evil Posted April 9, 2012 Report Share Posted April 9, 2012 If you're on about mine I got the original numbers mixed up, should have been 245/70 and 245/75's giving an 8cm diff which according to the site below would also be 8cm as philr said http://www.kouki.co.uk/utilities/visual-tyre-size-calculator Quote Link to comment Share on other sites More sharing options...
al4x Posted April 11, 2012 Report Share Posted April 11, 2012 The width of the tyre wont affect the gearing in any way however the profile height will, if you intend to use 4 wheel drive then the profile height should be the same as you will create different gear raitio's Balls The profile is a percentage of the width of the tyre so using different widths and the same profile will lead to problems. The correct answer in this case is its fine tyres are within 1mm rolling radius so effectively the same diameter. http://www.etyres.co.uk/tyre-size-calculator.htm Quote Link to comment Share on other sites More sharing options...
lumpy Posted April 11, 2012 Report Share Posted April 11, 2012 Balls The profile is a percentage of the width of the tyre so using different widths and the same profile will lead to problems. The correct answer in this case is its fine tyres are within 1mm rolling radius so effectively the same diameter. http://www.etyres.co.uk/tyre-size-calculator.htm Dear Mr Ball's Having done a couple of quick calculation's the true circumference of the op's front wheel's would be 895.83mm and the rear wheel's would be 896.86mm, Allowing for tyre wear this could fluctuate as much as 21.9mm, When i was at school (many moon's ago) these figure's would have been deemed as different, which in turn would create a torque imbalance. but hey ! maybe you know more than Land Rover's multi million pound research and development team :hmm: Quote Link to comment Share on other sites More sharing options...
al4x Posted April 12, 2012 Report Share Posted April 12, 2012 come on lumpy you were completely wrong in the first statement about profile, If discos can't have more worn tyres on one axle than the other which I think you're suggesting then there is something seriously wrong. Tyres do wear at different rates on axles and to an extent even 4x4's are designed to cope with it, bear in mind going round corners etc tyres don't cover the same distance as each other and you have things called diffs to cope with such things. When giving advice it helps if its right, on your first statement you could put 135 85 15's on the same vehicle as 235 85 15's and believe me it would look comical and be a very bad idea Quote Link to comment Share on other sites More sharing options...
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