titan Posted February 25, 2009 Share Posted February 25, 2009 iv been offered a set of bfg mt 285/75/r16 will these fit a defender or will i need to cut out the arches iv been told i will need a 2" lift just need to make sure this is correct will i need to make and changes to the gearing or anything not to sure what to do or how to do it but again just to no if i take them thanks shane Quote Link to comment Share on other sites More sharing options...
headhunter Posted February 25, 2009 Share Posted February 25, 2009 Should fit OK, close to the limit of tolerance. Others will be along to give you more precise advice no doubt. Have a look here - http://www.tyresite.com/tyrecalc.asp for tyre size comparison and effect on speedo reading. That will give you a clue to the change in gearing as well. John Quote Link to comment Share on other sites More sharing options...
white90 Posted February 25, 2009 Share Posted February 25, 2009 iv been offered a set of bfg mt 285/75/r16 will these fit a defender or will i need to cut out the arches iv been told i will need a 2" lift just need to make sure this is correct will i need to make and changes to the gearing or anything not to sure what to do or how to do it but again just to no if i take them thanks shane Too wide and not tall enough I'd wait and get some 255/85/16s watch out for the white/red/black 90 in this vid http://s114.photobucket.com/albums/n262/wh...rent=Movie2.flv it had those similar size tyres on it and even with ARBs couldbn't get up a muddy slope they pick up the mud and act like slicks Quote Link to comment Share on other sites More sharing options...
Ex Member Posted February 25, 2009 Share Posted February 25, 2009 They fit fine with no lift or modifications at all. You need proper wheels of the right width and offset. Most non-genuine 16x7" wheels are OK. They are the same height as 255/85/16. Quote Link to comment Share on other sites More sharing options...
scatt Posted February 25, 2009 Share Posted February 25, 2009 Firstly they will fit with no mods and no lift. i ran my 110 with 33x12.50 standard and it was fine on and offroad. 285x75 is just short of 33", the 255x85 are just over 33". Everyone has a different opinion about tyres size, tread, fitment etc. ive had this tyre problem thats why i know the sizes. Quote Link to comment Share on other sites More sharing options...
mel Posted February 25, 2009 Share Posted February 25, 2009 I'd agree with the above about being too wide as i think they'll just sit on top of the mud. One of the best tyres i had on an old 90 were "Firestone SATS" i thought they were excellent off road, abit hairy in the wet on road tho ! Quote Link to comment Share on other sites More sharing options...
titan Posted February 26, 2009 Author Share Posted February 26, 2009 thanks all ill see wat seal i can get i may look else where Quote Link to comment Share on other sites More sharing options...
T1G UP Posted February 26, 2009 Share Posted February 26, 2009 Too wide and not tall enoughI'd wait and get some 255/85/16s watch out for the white/red/black 90 in this vid http://s114.photobucket.com/albums/n262/wh...rent=Movie2.flv it had those similar size tyres on it and even with ARBs couldbn't get up a muddy slope they pick up the mud and act like slicks Obviously a MT pattern tyre wasn't suitable for that application regardless of the size. A more agressive pattern and less revs would result in a lot less damage to the gruond than was caused but spinning up on clogged MT's. I'll stick to my Insa's Quote Link to comment Share on other sites More sharing options...
white90 Posted February 26, 2009 Share Posted February 26, 2009 That ground was a pay/play site and thinner M/Ts got out of there ok too wide=slicks when full of mud. and they don't self clean enough. Quote Link to comment Share on other sites More sharing options...
titan Posted February 26, 2009 Author Share Posted February 26, 2009 so why are thinner better i would have thought wider would be better on lower pressure while ive been looking i get a bit confused with the sizes tbh is it better to stick with the 16s or drop to 15s?? Quote Link to comment Share on other sites More sharing options...
steven Hart Posted February 27, 2009 Share Posted February 27, 2009 Firstly they will fit with no mods and no lift. i ran my 110 with 33x12.50 standard and it was fine on and offroad. 285x75 is just short of 33", the 255x85 are just over 33". Everyone has a different opinion about tyres size, tread, fitment etc. ive had this tyre problem thats why i know the sizes. Even calculating this out they is 3mm(radius) difference 255x0.85= 216.75 285x0.75=213.75 cross-sectional height is actual 216mm (same as 33" tyres) The percentage figure given is rough guide rounded to the nearest .05%. 285's on my 110 are exactly the same size as my friends 225s although I have though of going over 255's as I have experienced floatation problems which my friends 90 doesn't Quote Link to comment Share on other sites More sharing options...
T1G UP Posted February 27, 2009 Share Posted February 27, 2009 pressure exerted over a given area. If you wife stood on your food in no shoes it would hurt. If she had a pair of stilletoes on and she stood on your foot....... Quote Link to comment Share on other sites More sharing options...
foggy3061 Posted February 27, 2009 Share Posted February 27, 2009 Firstly they will fit with no mods and no lift. i ran my 110 with 33x12.50 standard and it was fine on and offroad. 285x75 is just short of 33", the 255x85 are just over 33". Everyone has a different opinion about tyres size, tread, fitment etc. ive had this tyre problem thats why i know the sizes. Using this handy calculator: Tyre size calculator I get the 265/75-16 to be 32.83" and the 255/85 - 16 to be 33.07". 235/85-16 come out at 31.73" so even with 255/85-16 fitted you will achieve a 1.34" (34.036mm) increase in overall diameter. Therefore only 0.67" (17.018mm) extra ground clearance. Just out of interest! Quote Link to comment Share on other sites More sharing options...
Ex Member Posted February 27, 2009 Share Posted February 27, 2009 OK, ground pressure.... Ground pressure is basically equal to the air pressure in the tyre. If you want lower ground pressure, reduce the air pressure. A wider tyre AT THE SAME air pressure has a shorter, wider footprint than a narrow tyre. That type of footprint does not provide as much traction. However, a larger (wider or taller) tyre can be operated at a lower pressure safely. So, if you take a 285 and run it at its proper lowest pressure and the 255 at its lowest pressure then the 285 will do better. The problem is people not setting their tyres at the proper pressure (75 to 80% of maximum sidewall height). Quote Link to comment Share on other sites More sharing options...
titan Posted February 27, 2009 Author Share Posted February 27, 2009 OK, ground pressure....Ground pressure is basically equal to the air pressure in the tyre. If you want lower ground pressure, reduce the air pressure. A wider tyre AT THE SAME air pressure has a shorter, wider footprint than a narrow tyre. That type of footprint does not provide as much traction. However, a larger (wider or taller) tyre can be operated at a lower pressure safely. So, if you take a 285 and run it at its proper lowest pressure and the 255 at its lowest pressure then the 285 will do better. The problem is people not setting their tyres at the proper pressure (75 to 80% of maximum sidewall height). this is what i thought but then im not that tech minded i fugured the 285 would be ok as i said ill see what deal i can get Quote Link to comment Share on other sites More sharing options...
Ex Member Posted February 27, 2009 Share Posted February 27, 2009 The moral of the story... If you get bigger tyres, run lower pressures. I suggest everyone measure the sidewall height vs pressure for their own setup. 100% is at say 40 psi. A good running point is 85% of this height to start down to around 75% as a minimum. You need to do it front and rear as many vehicles weigh different front and rear. Quote Link to comment Share on other sites More sharing options...
titan Posted February 27, 2009 Author Share Posted February 27, 2009 so in theroy then instead of running at 40psi would be better running at 34psi ????? or is it a bit more tech than that Quote Link to comment Share on other sites More sharing options...
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