Forum Discussion

FLGup's avatar
FLGup
Explorer
Jun 27, 2014

P tires vs LT tires - tire sales conflicting info

OK, its time for new tires and after visiting 5 different tire stores and our local Ford dealership, I keep getting conflicting information. So....I need your real world experience.

I have a Ford F-150 (2wd) xlt crew cab that has Michelin P265/60R18 tires on it now.

I tow a 6000 lb 26' KZ Spree travel trailer. Weight dist. and sway control, of course.

It tows fine with the P265 tires but I've always read that LT tires are best, so when I asked, everyone said they do not make a LT tire in the 265/60-18 size. Ford dealership said to not change size, as it would screw up the speedometer, computer, etc. and that it wasn't necessary. Several of the other tire stores agreed with the dealership and said stay with what you have. Two tire stores said I should change. I would have to go to a 275/65R18.

Sooooo......what is right? IF I changed tire size would I screw up more than a mile or two on the speedometer? Would it ride hard and rough as they said? Would I screw up other computer settings?

Should I stay with P265/60R18 or change?

I plugged the info into this tire size calculator but I'm not sure what the data is telling me.

Any thoughts or real world input?

thanks for all the help.
Tow Vehicles
  • spoon059's avatar
    spoon059
    Explorer II
    Jun 27, 2014
    Golden_HVAC wrote:

    LT truck tires do not suffer from derating. However they are also only rated at about 75 MPH, and if above that speed, then LT tires must be derated by 10% weight factor as well.

    I had never heard of that before, so I just checked my BF Goodrich tires. According to BF Goodrich, if LT tires do not have a specific speed rating, they are rated to 87 MPH.

    Looking online, I don't se a specific speed rating for mine. I guess they are "only" rated to 87. Never realized that before!

    OP, if you don't have any problems with your current P rated tires I wouldn't change them. If you feel uneasy because they are squishy or you are close to your max rating, changing to LT will firm up the ride and most likely give you a higher weight rating. P tires are cheaper and offer a softer ride, which is why a lot of half ton trucks come with them.

    My Tundra came with E rated tires from the factory and I love them. When its time to replace, I'll probably go with a D range because the E range is WAY overkill.

    I wouldn't worry about 2 or 3 MPH faster or slower. If you change them, just remember the difference when driving.
  • time2roll's avatar
    time2roll
    Nomad
    Jun 27, 2014
    Try not to solve problems that don't really exist.
    Stick with the oem size.
  • intheburbs's avatar
    intheburbs
    Explorer
    Jun 27, 2014
    E load tires on a half ton? Probably overkill.

    That being said, I went to an E load tire on my half ton Burb. Wasn't available in the OE size (265/70/16), so I got a slightly smaller tire (245/75/16). Wanted the extra sidewall strength for towing and offroad driving.

    You can have your PCM retuned to make the speedo accurate once again. I never did. It was off by roughly 3% on the high side.

    Added side benefit - a sligtly smaller tire is like slightly increasing your axle ratio - should help a little bit when towing a big trailer.
  • ScottG's avatar
    ScottG
    Nomad
    Jun 27, 2014
    No offense but those coopers aren't LT tires either, especially with a max pressure of 50 psi and 2600#. There's nothing that suggests they have stiffer sidewall since they don't have a letter load range rating. Keep in mind that a rated load in lbs has little to do with sidewall stiffness. That's where the LR E rating comes in and that's where a true LT tire shines.
    I would hold out for a true LT tire if you can find one - or even replace the wheels to facilitate them.
  • Terryallan's avatar
    Terryallan
    Explorer II
    Jun 27, 2014
    Here you go. You can get Cooper Discoverer HT Plus in your size. They are NOT P tires. They are rated to 2601lb each, and do a great job towing. AND they are not real expensive, AND there is a $60.00 mail in rebate this month, and parts of July. Here is what I bought.

    Cooper Discovery HT Plus 114T. UTQG 460A, Max load 2601lb at 50 psi. 265/60/R18 Build date 1314 / April, this year. Made in USA.
    They do only come in BLK wall
  • ScottG's avatar
    ScottG
    Nomad
    Jun 27, 2014
    The problem is you asked the two sources that know the least about the subject; The dealer and a tire shop.
    Doing research on your own as folks have here, will get you better answers.
  • Golden_HVAC's avatar
    Golden_HVAC
    Explorer
    Jun 27, 2014
    Hi,

    According to the Michelin tire inflation and weight guide, when Passenger tires are installed on a truck, then the weight rating should be de-rated by about 10% (or was it 15%?). So a 'P' tire rated at 2,000 pounds is really only good for 1800 or 1700 pounds while mounted on a truck.

    LT truck tires do not suffer from derating. However they are also only rated at about 75 MPH, and if above that speed, then LT tires must be derated by 10% weight factor as well.

    Most 'P' tires are rated at 87 MPH, while some are rated as high as 135 MPH, and specialty tires rated at 185+ MPH. But that speed rating is only during the first 5 years after manufacture, then who knows what will happen to a tire at 150+ MPH?

    Personally I would change to the stiffer sidewall LT tires. Have you ever noticed that the front of the trailer can push the back of the truck a bit sideways while going down a hill? LT tires are stiff enough to prevent this.

    Fred.
  • transamz9's avatar
    transamz9
    Explorer
    Jun 27, 2014
    flguppie wrote:
    OK, its time for new tires and after visiting 5 different tire stores and our local Ford dealership, I keep getting conflicting information. So....I need your real world experience.

    I have a Ford F-150 (2wd) xlt crew cab that has Michelin P265/60R18 tires on it now.

    I tow a 6000 lb 26' KZ Spree travel trailer. Weight dist. and sway control, of course.

    It tows fine with the P265 tires but I've always read that LT tires are best, so when I asked, everyone said they do not make a LT tire in the 265/60-18 size. Ford dealership said to not change size, as it would screw up the speedometer, computer, etc. and that it wasn't necessary. Several of the other tire stores agreed with the dealership and said stay with what you have. Two tire stores said I should change. I would have to go to a 275/65R18.

    Sooooo......what is right? IF I changed tire size would I screw up more than a mile or two on the speedometer? Would it ride hard and rough as they said? Would I screw up other computer settings?

    Should I stay with P265/60R18 or change?

    I plugged the info into this tire size calculator but I'm not sure what the data is telling me.

    Any thoughts or real world input?

    thanks for all the help.


    If I had no problems with the OE tire and you are with-in the OE tire's weight specs I would just stay with the OE tire. JMO of coarse.;)
  • FLGup's avatar
    FLGup
    Explorer
    Jun 27, 2014
    Here is the info from that tire calculator site....



    Speedometer Difference

    Speedo Reading Actual Speed
    20 mph (32.19 km/h) 21.02 mph (33.83 km/h)
    25 mph (40.23 km/h) 26.27 mph (42.28 km/h)
    30 mph (48.28 km/h) 31.53 mph (50.74 km/h)
    35 mph (56.33 km/h) 36.78 mph (59.2 km/h)
    40 mph (64.37 km/h) 42.04 mph (67.65 km/h)
    45 mph (72.42 km/h) 47.29 mph (76.11 km/h)
    50 mph (80.47 km/h) 52.55 mph (84.57 km/h)
    55 mph (88.51 km/h) 57.8 mph (93.02 km/h)
    60 mph (96.56 km/h) 63.06 mph (101.48 km/h)
    65 mph (104.61 km/h) 68.31 mph (109.94 km/h)

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