Forum Discussion

samhain7's avatar
samhain7
Explorer
May 14, 2015

Tire pressure question

Hi all.
Apologies again for being the guy that seems to be asking too many questions. I am taking the safety of my family very seriously, so please no guy slapping himself in the forehead icons...
;)

My trailer weighs 7126lbs dry. We are heading out tomorrow.

I have Towmaxx STR tires (yes, I know junk, garbage get rid of them as soon as I can). On the sidewall and tires it reads:

ST225/75R 15D 65 PSI

Maxload single 2540 lbs at 65psi
Maxload Dual 2200LBS at 65psi

So the two questions are, should I be pumping up these guys to 65 psi?

Also, they were at 55psi when I just checked them. I towed them home from storage at that (about a 30 min drive), did I do some damage to them?
:S
LOL
  • AH64ID's avatar
    AH64ID
    Explorer
    May 14, 2015
    Looking at the specs of the trailer the GVWR is 8500lbs, which means the TAW will range from 7225 - 7650 at GVWR with 10-15% TW.

    That's just based on operating at GVWR.

    7650 is 1912/tire. If you round up to 2000/tire for a little wiggle room them you only need ((2000/2540)*65) 51 psi per tire. 55 psi is plenty of air and you won't have damaged them from that pressure.

    If you are doing short trips at speed of 55-60 then 55 psi is plenty, but for extended freeway trips at 60-65 then 65 psi would be better.

    Again, hitting the scales is the best answer.
  • coolbreeze01's avatar
    coolbreeze01
    Explorer
    May 14, 2015
    samhain7 wrote:
    Hi all.
    Apologies again for being the guy that seems to be asking too many questions. I am taking the safety of my family very seriously, so please no guy slapping himself in the forehead icons...
    ;)

    My trailer weighs 7126lbs dry. We are heading out tomorrow.

    I have Towmaxx STR tires (yes, I know junk, garbage get rid of them as soon as I can). On the sidewall and tires it reads:

    ST225/75R 15D 65 PSI

    Maxload single 2540 lbs at 65psi
    Maxload Dual 2200LBS at 65psi

    So the two questions are, should I be pumping up these guys to 65 psi?

    Also, they were at 55psi when I just checked them. I towed them home from storage at that (about a 30 min drive), did I do some damage to them?
    :S
    LOL


    You are fine. Your tires are as good or better than 95% of the ST tire brands. Have Fun.
  • SALEM1's avatar
    SALEM1
    Explorer
    May 14, 2015
    rbpru wrote:
    What does the TT manufacturer recommend for tire pressure? My owner's manual for the ST205/75 R 15 tires, states 50 PSI for my 5000 lb. dry weight TT.


    From the OP tire description ST225/75R 15D 65 PSI, the D after 15 stands for load range D (8 ply rating) with 65# max pressure. Your tires ST205/75 R 15 are load range C (6 ply rating) with 50# max pressure.
  • MNRon's avatar
    MNRon
    Explorer
    May 14, 2015
    Don't stress about pulling the trailer home, small chance of any problems unless you recall pulling over a curb at 20mph or something. Don't worry.

    Pump them up to 65psi, that's where they want to run and will perform best. Vast majority of tire damage occurs from under inflation, not because of too much pressure.

    Enjoy your trip!
  • rbpru's avatar
    rbpru
    Explorer II
    May 14, 2015
    What does the TT manufacturer recommend for tire pressure?

    My owner's manual for the ST205/75 R 15 tires, states 50 PSI for my 5000 lb. dry weight TT.
  • AH64ID's avatar
    AH64ID
    Explorer
    May 14, 2015
    Is that brochure weight or scale weight?

    65 psi is safe, but I would stop by a scale and get a good loaded axle weigt. Too much pressure will decrease tration, tire life, and increase suseptibility to road hazads.
  • MFL's avatar
    MFL
    Nomad II
    May 14, 2015
    I agree, no damage, as long as you did not tow it 85mph.

    Yep, air up to 65 psi cold, good to go.

    Jerry

About Travel Trailer Group

44,029 PostsLatest Activity: Jan 28, 2025