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Thread: Looking for advice after multiple flats on Cooper AT3's with Discovery 4

  1. #11
    Join Date
    Mar 2016
    Orange County, CA
    Quote Originally Posted by stuartr View Post
    Their information says that it is a standard load with 2600 lbs rating. The tire was recommended by the Cooper importer here at the tire shop, and it was also highly recommended by Overland Journal...didn't they use it on LR4's as well? I could have confused the two things. In any case, I specifically asked the shop about the load rating when I bought them, and the guy said it would be fine, as it was the same or higher than the stock tires. Perhaps he was selling me a load of B.S. (would not surprise me anyway). That said, 2600 pounds per tire and a 7100 lb vehicle would mean that even with three tires, the load per tire is 300lbs lighter than the load rating. Does anyone know how much they lose upon airing down? I am not trying to avoid the inevitable if they are not strong enough, just trying to figure out what would constitute strong it enough just to increase the pressure, or do I need to buy five new tires for what will likely be 2000+ dollars in this country...

    P.S. I will definitely have them check for cracked wheels. That said, the PSI was never below 27 psi on the front for any amount of speed...stock said 34. I lowered them down to 27 for a mountain road where I was going slowly. I am staying an hour journey along a mountain road and for this trip, I have put the pressure at around 30-31 front (again, from 34) and 33-34 back from 37. I did not think these were super low, especially since the tire has quite a bit more sidewall height than the factory (the factory ratings are for 255/55R19, and mine are 265/65R18).
    Regarding the above in bold, having a 300 pound margin for any one tire isn't very much. For example, if you are on a trail with rocks or ruts and your right front wheel and left rear wheel are driving over a rock or high spot then they are carrying most of the vehicle weight, effectively almost doubling their normal load and far exceeding the 300 pound margin mentioned above. You may want to consider Cooper St Maxx, BF Goodrich KO2 or any other 3 ply sidewall tire in Load Range E as well as replacing those 18" wheels with a 16" so you have a larger, more forgiving sidewall that is less likely to get pinched as already discussed. The new Yokohama Geolandar G003 M/T has 3 plys as well (Available July 1 in the USA)
    2003 Montero Limited
    3.8L V6 6G75 5 Speed Auto
    Roof Rack, Kumho- AT-51's LT265-75-R16E, Air Lift rear bags, skid plates, rear recovery points added on, modified spare tire holder for larger tires, 2" home made front spacer lift, 30mm rear coil spacer (80 Series Landcruiser Polyurethane spacer from Ironman4x4)

    1984 Isuzu Trooper II, LWB, 3 Door, SOLD
    1986 Toyota 4x4, 31-10.5's, SOLD
    1992 Isuzu Trooper 3.2L, SOLD
    1993 S-10 Blazer 4x4 4.3L Vortec SOLD

  2. #12
    Join Date
    Sep 2015
    California / Neuchâtel, CH
    In my experience with the Discovery 3,4 you can't even air down that much on a non E rated tire before it gets seriously bulged out. It used to be a rule of thumb that the dealer specced tires for the cars only if they were rated to take the weight of each axle on on tire, IE two tires touching the ground instead of four.
    2006 Discovery 3
    1995 Discovery
    1990 110


  3. #13
    Join Date
    Dec 2015
    Ok, thank you all. I talked to another tire shop today (in another part of the country, where I currently am), and they said that the tires I have were among the best available in my size for the Discovery. They do not sell Cooper, so they had nothing to gain from telling me this. They only had Yokohama Geolandar ATS tires available in something similar. In any case, I had them just fix them up. I will look into the BFG's, but I think that no one here really has the correct tires available, nor do they seem to know much about the Discovery and what it needs. This is odd, as it is a very common car here.

    Offroadmuch -- I would love to get 16 or 17" wheels, but the very smallest possible on the D4 is 18", and only then with Compomotives. I am using the largest tires possible without lifting the car or modifying the wheel wells.

  4. #14
    Join Date
    Nov 2010
    Kansas City
    Cooper states that the E-rated AT/3 tires in 265/65/r18 are rated at 3305 lbs load.
    Current: LR4

    Former: JKU | FJ40 | FJ40 | FZJ80 | FJ60 | Discovery 1 | ZJ | XJ | Scout II

  5. #15
    Join Date
    Aug 2015
    Kailua, Oahu, Hawaii

    From what I can see, Cooper Discoverer AT/3 comes in a 265/65R18 in two different ratings; they come in a P265/65R18 114T (C Rated) advertised for use on SUV page and LT265/65R18 122R (E Rated) advertised on the Light Truck page.

    1) P265 with speed Rating T with Load Index 114 is for 2601lbs which by my research would be a "C" rated tire and not suitable for offroading air downed Disco 3/4 weight vehicles.
    2) LT265 with speed Rating R with Load Index 122 is for 3307lbs which by my research would be an "E" rated tire and I think the one rjl found as well. Much more suitable for the weight of the vehicle.

    The picture of your wheel clearly shows a 114T Load Index/Speed which signifies its most likely the P265/65R18 114T (C Rated). Although the C rated could meet the minimum spec of the vehicle, I do not believe it is the right tire for the conditions your vehicle is being operated and I am sure that is exactly what the saleman/warranty guy will tell you.

    Hope this helps out....I can post links if you want. Can you post a pick of the entire tire from the peripheral so we can zoom in on all the markings?

    Honestly I believe its the tire spec that is the problem here.
    Last edited by Victory_Overland; 06-20-2017 at 03:34 AM.
    Kailua, Oahu, Hawaii
    2008 LR3 SE (90K Miles)

    >>>Build Thread<<<

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  6. #16
    Join Date
    Oct 2014
    FL Keys, Iowa farm

    First, just wanted to say hello, and thanks! Thanks because the Icelandic people are some of the nicest I have ever met, and your country's landscapes and trails are amazing. Hopefully "Tread Lightly" catches on there to keep tourists in sedans from screwing it up.

    For your discussion, and "translation" of tire data, we Americans should look at this:

    That way we are all on same page.

    I don't think it is pinching, I think the tires are under spec, and maybe too aired down. We did a bunch of snowy/slippery F roads in April (our own rig, Defender 110 with new BFG TAs) and I aired down maybe 10 on rear and 5-10 on front. Are you in terrain that calls for you to air down as much as you are?

    You could always winch out using a tree
    Former Action Overlander

  7. #17
    Join Date
    Dec 2015
    Thanks guys. Yes, I think this is probably the issue, the spec of the tires. They seem to be good enough to get around in most conditions at standard pressure, but they are clearly not doing too well. Unfortunately, the tire shop probably will not acknowledge that...I might get a discount on new ones, but they will still probably be expensive. I am sure they do not have the E spec in stock, otherwise they would have offered them. The other shop told me there were not stronger tires available in that size, but as we know, that is not the case. In their defense, they probably mean that are readily available in Iceland. In the meantime, I have been running the tires at regular pressure (i.e. not airing down) over the gravel roads, and while the ride is a lot harsher, so far I have not had any more problems. When I get back to Reykjavik I will see what else I can do. The tire shop here was able to fix up one tire, and the other they patched and put in the spare spot, but they said that it was now junk, and that I should get rid of it as soon as possible, and only use it in an emergency to get back to civilization.

    KGH: There is no ice at the moment, and the roads are mostly dry, so I was airing down mostly because there is a lot of steep terrain with loose stones, and occasionally larger rocks or ruts. It is nothing super technical, mostly just steep and a bit slippery. I found that airing down gave me both a smoother ride and better traction. I don't feel that airing down was necessary to pass through the terrain, only to make it more pleasant. And yes, I would agree, treading lightly is important! Unfortunately, I think it is more of a case of not treading at all. Many of the areas that are being damaged by tourists can only support a few people a year...just walking on the moss can take decades to reverse. Unfortunately, Iceland is now a victim of its own popularity. In 2010, for example, from January to May we had 210,000 tourists. This year from January to May we have had 752,000. That is more than double the population, and that is during the low season (also the season when the nature is the most vulnerable). They expect over 2 million visitors this year, and in another year of two they expect we will have more visitors than New Zealand, which is more than twice the size and has more than four million locals. This is great for hotels, airlines, bus and car rental companies, and it has rejuvenated the economy, but it has been at a great cost to the character of the country and the environment.

  8. #18
    Join Date
    May 2013

    I have the same tires in P265/70/16 (stock size) on a stock 2003 4runner. I got a front flat right in the tread block going about 15 MPH on a pretty tame forest service road in Northern California. I posted someone's photo to give an idea of how the conditions were. The air was hissing out, and I stopped and changed it with about half the air left. Luckily no further damage and I was able to have the tire shop patch it without issues. This was at around 32 PSI.
    I have to say I'm extremely disappointed that the tires couldn't handle 30 minutes of such easy conditions, especially since the puncture happened in the thickest part of the tire tread. On an old F150, I used to have some BFG Mudders with 10% tread life that I beat on for over a year at high speeds trails with sharp desert rocks without issues.
    Last edited by guestwho; 07-29-2017 at 07:26 PM.
    '03 4runner v8, Bilstein 5100's, 265/70/16 Discoverer A/T3s

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