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Larger tires=plow adjustment????

Discussion in 'Boss Plows Discussion' started by kurtandshan, Dec 8, 2011.

  1. kurtandshan

    kurtandshan Senior Member
    Messages: 323

    Hi all, looking to go from 245 75 17s to 285 75 17 size tires. Will this require me to adjust the mount for 8.2 Vxt? Btw truck is 07 f250 ccsb. Thanks
     
  2. Earthscapes

    Earthscapes Senior Member
    from WNY
    Messages: 577

    You'll be fine.
     
  3. mnglocker

    mnglocker Senior Member
    Messages: 923

    If it was me, I would; but then again I'm anal and like my **** to last.
     
  4. bltp203

    bltp203 Senior Member
    Messages: 484

    If you have enough adjustment left to get it to 15.5 inches, then why not?
     
  5. randomb0b123

    randomb0b123 PlowSite.com Addict
    from america
    Messages: 1,278

    you probably wont know for sure til you have the new tires and the plow on? either way i want to subscribe to see what happens here and what solution is im curious
     
  6. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,552

    I want to know who the hell decided that 245 X 75 X 17 is a better way to define a tire than 32 X 10 X 17

    to find the diameter or width you have too do too much math.

    Diameter = ((245 *.75)*2 +17) then divide by24.5 to get inches

    so your going from a 32" tire to a 40 1/4 in diameter so the truck will sit about 4" higher So yes you will have to adjust the plow frame height

    Plus your going to reduce your gearing by ~ 30 % (tire circumference is going from ~800"/rev to 1,250"/rev)
     
  7. kurtandshan

    kurtandshan Senior Member
    Messages: 323

    I believe the 245 is roughly 31" and the 285 is about 33" (per specs). But I will pull tape on my mount as it sits with the current tires and when/if I get the new ones I will let you know the difference! Thanks for the help guys! I I have the 4:10s in my truck so I guess I should be alright as far as gearing. Who knows, maybe my mileage will get better! like from 9MPG to 9.5MPG!
     
  8. mnglocker

    mnglocker Senior Member
    Messages: 923

    If the 285's are 40" then the old lady will be really impressed tonight. :laughing::laughing::laughing::laughing:
    I think your tire formula is wayyyyy off.
     
  9. Mgbss

    Mgbss Junior Member
    Messages: 26

    Remember if your tires are 2" Taller your only raising your frame 1"
     
  10. Tony350

    Tony350 Senior Member
    Messages: 546

    His formula is close 245X.75= 183.75 millimeters from the rim to the top of the tire. Multiply by two because you also have from the rim to the bottom of the tire. 183.75X2=367.5mm. Now divide by 25.4 to convert this to inches 367.5/25.4=14.685 inches of tire (top of rim and bottom of rim) Next you have to add the diameter of the rim to the amount of tire you have. 14.685''+17''=31..685'' tall tire. The 285 would be
    285X.75=213.75mm
    213.75X2=427.5mm
    427.5/25.4= 16.83inches
    16.83''+17''=33.83''

    33.83-37.685=2.145 The difference in tire height. So you will raise the frame height of the truck 1.0725.

    Not trying to to get to technical but that is the formula for converting to inches. I would bet both tires run a little short. Most companies "cheat" to save rubber on tires making them a little smaller. I would agree mount them up and see how the aframe looks.
     
  11. jklawn&Plow

    jklawn&Plow Senior Member
    Messages: 469

    Does the formula account for how the tire sits flat on the bottom?
     
  12. theplowmeister

    theplowmeister 2000 Club Member
    from MA
    Messages: 2,552

    As tony350 said My math is close devide by 25.4 NOT 24.5 :eek:
     
  13. Tony350

    Tony350 Senior Member
    Messages: 546

    No it doesn't take that into account. It will vary with the weight of the truck or load and whatnot.
     
  14. MikeRi24

    MikeRi24 Senior Member
    Messages: 563

    to answer your original question, you shouldn't HAVE to change the mount, but if you can get it to 15.5" go for it. I have 285s on my truck for the summer and switch back to 245s for winter. When I started moving my plow around to get it ready while I still had the 285s on, I had to get the floor jack out and under the plow to raise it up a little to compensate, and then had to do the same when I put the 245s on. Once you get over that, the plow jack itself will lower to the correct height, but as I said, if you can safely lower the mount, do it.
     
  15. Mr. Mud

    Mr. Mud Member
    Messages: 91

    Your profile says you are from Iron Mountain Michigan, I figured everybody walking up and down the street would be a walking talking boss expert. I used to jack around with changing tire sizes and treads from winter to summer, it just isn't worth the headache. I've stuck with the 245's for the last 15 years, must be getting old and crabby.
     
  16. kurtandshan

    kurtandshan Senior Member
    Messages: 323

    I am indeed from Iron Mountain, home of the Boss....yes I am a walking talking Boss expert...lol I am not, however, a walking talking tire size/frame height mechanical engineer type. I am also, old and crabby, but the 245s just seem like donuts on my truck.
     
  17. jklawn&Plow

    jklawn&Plow Senior Member
    Messages: 469

    I'm running my factory tire to the 1/32 why throw good money away.
     
  18. kurtandshan

    kurtandshan Senior Member
    Messages: 323

    I hear ya...not getting new ones until these are shot.
     
  19. Mr. Mud

    Mr. Mud Member
    Messages: 91

    I switched over to Cooper Discoverer STT's a few years ago, probably 8 or 9 by now. I don't think I could switch, as they have saved me numerous times! They are not a high life tire as I have managed only about 35 K with them, but they go 2 full winters and that's well worth it. I think I gave about $185 each for the new set a couple months ago. Just got them mounted on the new truck still trying to get enough energy to put the plow together and get it mounted! MUD