Tyres Light truck or passenger

Submitted: Saturday, Mar 08, 2003 at 21:50
ThreadID: 3726 Views:8153 Replies:7 FollowUps:2
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I am confused with tyres. I am getting close to having to change and I just can't understand the tyre jargon. I assumed that all the all terrain tyres were light truck last time I got tyres on another car. I soon found out that even though they were aggressive all terrain they were still only rated as passenger tyres.

Having looked around I find that most of the tyres that say light truck are still only two ply tyres. So what is the diffence then with the passenger all terrain tyres apart from the load rating maybe. I have checked out my existing tyres and load rating anfd they are within the specifications.
I am looking at
265/70/16 but apart from BFG's nothing seams to be avail with the extra plys.

Secondly if tyres such as dert duellers etc are not meant for desert or gibbers then why advertise them as such. I have found a Bridgestone tyre which is light truck and about 10 ply and using 245/75/16 will have no speedo error. But now I wonder if they will be hard as a rock on the black top.
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Reply By: Jol Fleming - Saturday, Mar 08, 2003 at 22:05

Saturday, Mar 08, 2003 at 22:05
Passenger plys are a lot lighter than passenger, ie smaller cord and steel.
same tyre can be heavier, 2 ply side walls are norm or they dont flex,

All the extra plies are in the tread, get a good set of 265/75/16 you want thicker you'll shake the car to bits, and learn where your wheels are, miss the sticks and stones
AnswerID: 14686

Follow Up By: David - Sunday, Mar 09, 2003 at 07:57

Sunday, Mar 09, 2003 at 07:57
I have a Prado and two problems with the 265/75's is that they scrape on the front fender liner at times and secondly they do alter the gearing significantly. Where I live is quite hilly and I found the constant auto changing annoying whereas when I went back to standard size the problem was fixed. Maybe it would be ok now I have a diesel, maybe it would hold the gears better but it is expensive if I don't get it right the first time.
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FollowupID: 8891

Reply By: Eric - Saturday, Mar 08, 2003 at 23:00

Saturday, Mar 08, 2003 at 23:00
David.
The tyre catalogues list recreational tyres and light truck seperately, recreational tyres are flimsy compared to truck tyres. If you want long life with very few punctures go for 750R16 on split rims and run them at a pressure that allows the tyre to bag out a little this will give a good ride with better traction. The split rim enables you to fix the odd puncture without any fancy tools even with 8 ply tyres. Eric.
AnswerID: 14696

Follow Up By: David - Sunday, Mar 09, 2003 at 08:01

Sunday, Mar 09, 2003 at 08:01
I understand that but the dilemma I have is that most of the LT tyres in my size have no more ply's than the tyres I have now. I don't want to change rims as well but I understand the benefits of the old "skinny wheel"
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FollowupID: 8892

Reply By: Member - Colin- Sunday, Mar 09, 2003 at 00:24

Sunday, Mar 09, 2003 at 00:24
Another point is the speed rating - LT tyres generally will have a lower speed rating which could be a problem if you have to pass rego checks as in NSW, Although HT and AT have the same number of plys, the AT are stronger/stiffer in the side wall. I replaced the Bridgestone DD H/T on my Forester with A/T's and the difference is very noticable - visually, on road and off road. Not up to 'bullet proof' BFG or Coopers etc. but a good compromise for my use
AnswerID: 14700

Reply By: David - Sunday, Mar 09, 2003 at 07:52

Sunday, Mar 09, 2003 at 07:52
Thanks for your responses so far guys but I guess what I was asking is

1. "are the majority of AT tyres just the same as highway tyres with a more agressive tread?"

2. As the majority of A/t tyres seem to be passenger rated or if marked as LT are only a couple of plies. can they be used across the desert, gibbers etc.

3. Why are some tyres of the same brand ie BFG's different ply rating eg 260/70/16 2ply sidewall 265/75/16 3ply sidewall. Both are marked light truck.



AnswerID: 14707

Reply By: Jim - Sunday, Mar 09, 2003 at 20:13

Sunday, Mar 09, 2003 at 20:13
David,
I can't amswer all your queries, but my understanding on radial tyre ply rating is that there are two aspects - one is the "rating", which is an attempt to compare the topughness/ load carrying etc with the old cross ply tyres; eg "4,6 or 8 ply rating". The other is the actual construction which is of two plies - technical reasons. The higher rating means thicker tyres with more weight carrying capacity and more puncture resistance.
My understanding also is that the major difference between passenger tyres and light truck tyres is the same - Lt's can carry more weight and have more puncture resistance. The information on load and maximum pressure allowable in the tyre is usually on the side wall of the tyre near the size info.
Your local tyre bloke should be able to help. Failing that, ringing the technical services section of a tyre manufacturer can br useful.
Hope this helps.
Jim
AnswerID: 14738

Reply By: jason - Monday, Mar 10, 2003 at 16:05

Monday, Mar 10, 2003 at 16:05
david,the difference between passenger rated tyres @ LT tyres is simple.even though they are the same ply rating the LT use thicker steel cord in the tyre to be tougher & generally, the maximum pressure you can run in a LT is higher than a passenger.as far as tech goes,from my understanding , you can put LT tyres on a vehicle which is placarded passenger (as long as the load & speed ratings comply) but you cannot put passenger tyres on a vehicle placarded LT.some vehicles are duel placarded which means you can put either passenger or LT as long as they comply with load & speed ratings.other vehicles (eg GU patrol) can have a replacement tyre placard fitted which is available through the vehicle manufacturers spare parts.with the tyres you are looking at, extra ply's don't always mean extra strenght.it comes down to how thick the cords are.if you are looking to travel on gibbers,talk to the tech advisors of the relevant tyre companies.they can provide you with all sorts of information on how far the tyre will distort in the tread with a rock impact before it will fracture.they can also advise on correct tyre pressures to run in certain situations. from my what i have read the bridgestone 693 AT has one of the best tread impact resistance around & is also one of the best AT's for on road handling.my response to you comment on the 10 ply bridgestone is that it depends on where the extra ply's are that will determine the comfort level.my last bit of advice is if your going of road (apart from sand) stay clear of passenger rated tyres.
regards
jason
AnswerID: 14778

Reply By: jaycee - Thursday, Mar 13, 2003 at 20:17

Thursday, Mar 13, 2003 at 20:17
Jason is pretty spot on. The light truck tyres have thicker plies (cords) this means they can carry heavier loads however they will also have a lower speed rating, ie will overheat quicker as the thicker plies do not allow the tyre to disapate heat as quickly as the passenger rated ones. As far as three ply versus two ply go, dont stare yourself blind that the three plies are better as the overall ply thickness is no different to the two ply, otherwise the tyre would overheat quicker for the aforementioned reason. If you are carrying reasonable loads of gear for off road and dont go much harder than 120km/hr on road go with the light truck. I run Dunlop Adventurers 31.5x10.5x15 (the metric equivalent) in light truck and only just now replaced them after 83,000 kms and they were still legal (just).
AnswerID: 15124

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