slihp Posted May 6, 2011 Share Posted May 6, 2011 I have BF Goodrich Mud Terrain on just now, but may be looking to get a full new set of tyres the truck has a 2'' lift kit and 255/85/R16. there is so many tyre sizes and as always the ones i like dont come in this exact size but slightly different. Im looking for a good explanation to what these sizes mean (i know r16 is the radius of the rims) and what rage of tyre i can go for. thanks guys. Quote Link to comment Share on other sites More sharing options...
western Posted May 6, 2011 Share Posted May 6, 2011 255 = tread width in millimetres 85 = % of tread width & is the sidewall height so 85% of 255mm I have 255/85 MT on my 110, you'll gain approx 1 inch more clearance under the diff housings Quote Link to comment Share on other sites More sharing options...
crclifford Posted May 6, 2011 Share Posted May 6, 2011 My understanding of the dimensions are 255 = Width of Tyre 85 = Percentage of the width giving the height from edge of wheel rim to outside of the tyre (your case if you measure your tyre you should have 216 or 217mm from wheel rim to thread) R16 = as you know is the radius of the rims. Another factor to check is the width of the wheel rim and that you can fit your new chosen tyres to it as well. Can't help you with what to replace your old ones with as i'm confused on that as well! As far as i can tell, you should choose a tyre that matches what you want from it ie On road performance v off road performance etc. HTH and i'm sure someone else will be along that might be able to give you a better steer. EDIT:---Ralph beat me too it!! shouldn't type so slowly!! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 6, 2011 Share Posted May 6, 2011 R16 = as you know is the radius of the rims. Diameter not radius! Quote Link to comment Share on other sites More sharing options...
crclifford Posted May 6, 2011 Share Posted May 6, 2011 Diameter not radius! ok..my bad!! Quote Link to comment Share on other sites More sharing options...
slihp Posted May 6, 2011 Author Share Posted May 6, 2011 so it is the percentage figure (in conjunction with the tyre width) that dictates if you have clearance from the wheel arch that is your main concern, yes? Quote Link to comment Share on other sites More sharing options...
western Posted May 6, 2011 Share Posted May 6, 2011 biggest that will fit without fitting a suspension lift is 235/85x16, almost equal to the 7.50x16 [7.5 inches wide] that used to be factory fit. Quote Link to comment Share on other sites More sharing options...
slihp Posted May 6, 2011 Author Share Posted May 6, 2011 man this is so confusing but its time i understood it. so like you western i have 255/85/r16 therefor my tyre width is 255mm my sidewall height is 216.75mm (85% of tyre width) rim radius is 16 i have 2'' lift on mine. so as long as the sidewall height of which ever new tyre i choose docent go above 216 they will fit? can i go with a bit bigger side wall as there is about 2-3'' space between tyre and wheel arch (truck unloaded). also how can i tell what the max width my rims will take, for example im looking at 285/75/r16 will these be two wide for the rims. and finally is it an MOT failure if the tyres protrude further than the wheel arches? thanks for the info guys. Quote Link to comment Share on other sites More sharing options...
western Posted May 6, 2011 Share Posted May 6, 2011 285/75 is 30mm wider but 5% less height so they should fit, than a 255/85 tyre, but you will need to adjust the steering stops, so the inner shoulder is clear of the radius arms. a 6.5 [xd/wolf] rim will accommodate 255 tyres, that's what my 110 is wearing, any wider you'll need 7 or 8 inch wide rims. tyre tread area must be covered by the body or wheel arch/flexi flare when viewed from directly above [looking down] to be MOT passable Quote Link to comment Share on other sites More sharing options...
slihp Posted May 6, 2011 Author Share Posted May 6, 2011 ok think i have got everything answered. I have mach 5 rims so just need to find out what the max width they will take. cheers guys Quote Link to comment Share on other sites More sharing options...
slihp Posted May 9, 2011 Author Share Posted May 9, 2011 as a side note on this topic, as said i have 255/85/r16 and they are just about flush with the wheel arches so how can other defender owners legally run anything wider than 255, would these not protrude further than the wheel arches and be an MOT failure? or is it 1) you can get bigger wheel arches or 2) different rims offset the tyres differently. cheers Quote Link to comment Share on other sites More sharing options...
crclifford Posted May 9, 2011 Share Posted May 9, 2011 as a side note on this topic, as said i have 255/85/r16 and they are just about flush with the wheel arches so how can other defender owners legally run anything wider than 255, would these not protrude further than the wheel arches and be an MOT failure? or is it 1) you can get bigger wheel arches or 2) different rims offset the tyres differently. cheers I have 235/70/R16 General Gradder UHP on my 90 on 30mm spacers...and they pass the MOT...just about!!! However i belive you can get wider arches, or make your own out of old conveyor belt (as i think a few people on here have done this) HTH Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 9, 2011 Share Posted May 9, 2011 Wheel arch cover of the road wheel is NOT a testable item, therefore it cannot fail for having it's wheels sticking out the arches. The requirement for adequate wheel arches is from Construction and Use regulations, in other words you can get nicked for it. Quote Link to comment Share on other sites More sharing options...
slihp Posted May 9, 2011 Author Share Posted May 9, 2011 sorry bowie im confused now. are u saying mot failure is if the wheels stick out past the body Quote Link to comment Share on other sites More sharing options...
western Posted May 9, 2011 Share Posted May 9, 2011 sorry bowie im confused now. are u saying mot failure is if the wheels stick out past the body No, it's just not in the test schedule, so can't fail, if they are slightly outside. Quote Link to comment Share on other sites More sharing options...
slihp Posted May 9, 2011 Author Share Posted May 9, 2011 so what is it bowies talking about you can get nicked for Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted May 9, 2011 Share Posted May 9, 2011 It's not an MOT fail, but it's a motoring offence to do with the Construction and Use Regulations if your wheels stick out the arches. MOT is not the law, only a safety inspection. Quote Link to comment Share on other sites More sharing options...
slihp Posted May 9, 2011 Author Share Posted May 9, 2011 right gotya Quote Link to comment Share on other sites More sharing options...
landy V8 Posted May 10, 2011 Share Posted May 10, 2011 i'm running 35/12.5/15 on my 110 with a 2" lift.they're 15x10 with -32 offset.i've got +2" extended arches and they still stick out,but it still passed MOT. Quote Link to comment Share on other sites More sharing options...
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