pugwash Posted March 24, 2008 Share Posted March 24, 2008 Currently running 285/76r16 BFG MTs on the truck but dont have a spare. i do have 2 285/75R16 BFG ATs in the garage at home. As they are both the same size is their any reason why i shouldn't carry the ATs as a spare and run an MT and an AT on the same axle if i have to? Quote Link to comment Share on other sites More sharing options...
OilIT Posted March 24, 2008 Share Posted March 24, 2008 Currently running 285/76r16 BFG MTs on the truck but dont have a spare. i do have 2 285/75R16 BFG ATs in the garage at home. As they are both the same size is their any reason why i shouldn't carry the ATs as a spare and run an MT and an AT on the same axle if i have to? I thought that the /76 versus the /75 referred to the sidewall size as a percentage of the tyre width - which means the AT's are slightly smaller than the MTs in overall diameter - wouldnt this (if i'm right) cause diff windup if used on the same axle? i'm sure somebody will be along who can tell me i'm wrong or right ! jerry Quote Link to comment Share on other sites More sharing options...
Night Train Posted March 24, 2008 Share Posted March 24, 2008 I thought that the /76 versus the /75 referred to the sidewall size as a percentage of the tyre width - which means the AT's are slightly smaller than the MTs in overall diameter - wouldnt this (if i'm right) cause diff windup if used on the same axle?i'm sure somebody will be along who can tell me i'm wrong or right ! jerry By a quick calculation: 285/76R16MT = 839.6mm diameter and 2637.7mm circumference 285/75R16AT = 833.9mm diameter and 2619.8mm circumference The MT turns 99.3 times for each 100 times the AT turns. E&OE as I didn't sleep last night and I am knackered. Quote Link to comment Share on other sites More sharing options...
glaggs Posted March 24, 2008 Share Posted March 24, 2008 When making tyres, the side wall height and tyre width have to be within 10% tolerence to qulifie for the size/aspect ratio rating on the side wall. Different makes of tyre - even though the size on the side wall is the same may have a different rolling circumference and therefor if fitted to the same axel cause the diff to work harder. Tyres from the samm manufacturer with a different tread pattern, but marked as being the same size may also give the same problems. Then you will have differing levels of grip from the two tyres. As a limp home carfully option you should be OK, but wouldn't recommend it long term. Quote Link to comment Share on other sites More sharing options...
BogMonster Posted March 24, 2008 Share Posted March 24, 2008 I suspect /76 is a typo and they are actually the same size, I have never heard of a /76 anything! Also the words "As they are both the same size" sort of gave it away No problem for using as a spare IMHO, just be careful stopping in a hurry in the wet. AFAIK there is no MOT regulation about tyres all having to be the same tread pattern. Quote Link to comment Share on other sites More sharing options...
western Posted March 24, 2008 Share Posted March 24, 2008 I'd say Pugwash has dropped a typo too. http://www.camskill.co.uk/products.php?pli...11219&rs=gb as a get home it'll be fine Quote Link to comment Share on other sites More sharing options...
Pete Attryde Posted March 24, 2008 Share Posted March 24, 2008 As the tyres are the same size I can't see it being a problem as a get you home option, Especially when you consider the horrible space saver spares a lot of new cars now come with. Pete. Quote Link to comment Share on other sites More sharing options...
smo Posted March 24, 2008 Share Posted March 24, 2008 It'll be just fine, the 75/76 is a type for sure! I've used smaller/larger tyres to get home 10miles or so from playing without problems (eg: 235/85 spare when others are 265/75) Quote Link to comment Share on other sites More sharing options...
Scotian Posted March 24, 2008 Share Posted March 24, 2008 I;ve been using my spare tyre for the past few thousand miles due to location and not being able to afford to get Colway MTs over here. on 3 corners I've got Colway MT 265/75s and on the rear right i;ve got a Colway MT 265/70 that is also very worn compared to the opposit tyre. I havent noticed any difference in handeling but there is now alot of play in my drive train. This could be from normal wear for the type of driving I'm doing or maybe now from reading this its caused by the tyre size difference... I've got a pair of part worn 265/75 MT tyres of inknown make on their way through a local back streen tyre place for 200 lei (about 40 quid) so hopefully this will stop any more damage. Quote Link to comment Share on other sites More sharing options...
ThreePointFive Posted March 24, 2008 Share Posted March 24, 2008 Would a 265/75 be ok as a spare for 265/70s? Purely for a get-me-home tyre. Quote Link to comment Share on other sites More sharing options...
smo Posted March 24, 2008 Share Posted March 24, 2008 Would a 265/75 be ok as a spare for 265/70s? Purely for a get-me-home tyre. Yup, fine Quote Link to comment Share on other sites More sharing options...
JST Posted March 24, 2008 Share Posted March 24, 2008 Puggy that sort of implies the truck is running if you are thinking about spares take both of them - they will be fine. are Toyo 6 stud? Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted March 24, 2008 Share Posted March 24, 2008 Shouldn't make any difference from what James said about your driving Mo Quote Link to comment Share on other sites More sharing options...
pugwash Posted March 24, 2008 Author Share Posted March 24, 2008 They are both 285/75- apologies for typos. i presumed from the tire size that they would be ok, but i wondered if such different rates of traction could create issues of some sort- doesn't seem likely though. Toyo is 6 stud yes, just making sure that i have relevant spares! Quote Link to comment Share on other sites More sharing options...
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