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275/70r16(what size tire is that 31" 32" 33"????

Discussion in '80-Series Tech' started by raiderob, Feb 3, 2004.

  1. raiderob

    raiderob Regular Member

    Redwood City, CA.
    what is the true tire size in diamiter for 275/70R16
  2. Ronin

    Ronin Regular Member

    Western New York
    It should be around a 31 inches high and 10.5 in width, but it all depends on the manufacturer as they all vary even in the same size.
  3. sjcruiser

    sjcruiser New Member


    They slightly differ from manufactures & vary from types to types. The Michelins LTX & CrossTerrains are 31.2 in IIRC.

  4. landtank

    landtank SILVER Star

    Boston MA
    If your now looking at tires for that above mentioned spring install I'd recommend 285/75R16s and then drop in the speedo gear from slee to correct, well, the speedometer. 305/70R16s are basically the same overall diameter just a little wider

    Both will fit in the stock tire carrier!
  5. Mr.Bryan

    Mr.Bryan New Member

    Tinley Park, IL
    For future refrence, a way to kinda sorta basically figgure out within a half inch of what the tire size is: I'll explain as best I can. We'll use a 305/70/r16.

    Take the 305. That is 305 mm. wide. The side wall is 70% of that 305 hense the 70. so 70% of 305 is 213.5 now that is in mm. change it to centemeters: 21.35 now take those centemeters and change them to inches.

    1 centemeter is equal to .3937 of an inch. Multiply 21.35 by .3937 and you end up with 8.41 ( i rounded) now what that means is your side wall 8.41 inches tall. Now multiply the 8.41 by 2 because there are two side walls from the ground to the top of the tire.

    Now you have 16.82. Now you add in the R16. That is your rim size. 16.82+16=32.82 The tire is roughly 33" and tread depth also effects the actual size. That is something specific to each tire.

    But Basically that is kinda a simple way to figgure out what the tire size is. It seems more complicated then it actually is.

  6. Shortbus

    Shortbus Regular Member

    Vancouver, WA.
  7. SHAMROX80

    SHAMROX80 Regular Member

    In my House
    why not cut out the centimeter step and just multiply the mm by
    .03937 ;)
  8. MoJ

    MoJ Moderator

  9. nakman

    nakman addict. Supporting Vendor

    Broomfield, Colorado
    Ooo ooo me too!! width x sidewall x 2 x .03937 + rim. You can do this on your phone to impress girls.

    285 x .75 x 2 = 427.5. 427.5 x .03937 = 16.83, + 16 = 32.83
  10. MoJ

    MoJ Moderator

    BTW - since we're on the tire subject (no moans please).....Anyone have trouble (rubbing, steering, wear, etc) with width when running a 305 on a stock set up? (vs running the 285) (285=11.2 inches, 305=12 inches)
  11. Beowulf

    Beowulf New Member


    It depends on what you mean by trouble and how you're driving. I've seen the 305/70R16 MTR's rub slightly (i.e. some noise but didn't rip off the LR flare) on a rig with 850/863's. The truck was twisted pretty good; full droop on RR, full compression on LR, and a new set of aggressive tyres. This rig had the stock rear panhard so the body sat approx 1/2" to the right of stock giving less room in the LR wheel well.

    A stock rig may have a little less problem in this scenario because the panhard in a stock truck will have the axle centered. Then again, the stock truck might rub even more in a fully stuffed situation with no lift.

    For light wheeling with an A/T type 305 tyre and a stock suspension, you probably will not have a problem. You will be safer with the 285's though.


  12. landtank

    landtank SILVER Star

    Boston MA
    [quote author=Beowulf link=board=2;threadid=10971;start=msg98694#msg98694 date=1075848934]
    This rig had the stock rear panhard so the body sat approx 1/2" to the right of stock giving less room in the LR wheel well.

    B, I don't think this is accurate. Regardless of how the truck sits at rest, when the axle is twisted as you state, one end at full compression, I beleive the stock panhard length is ideal. Because full compression is full compression regardless of spring rate and the mechanicals position would be the same. A longer panhard rod would shift the axle either in or out depending on which side the compression was and cause more rubbing.
  13. Beowulf

    Beowulf New Member

    Hmmm. I'd have to think about that but your logic seems sound. I was thinking of the level starting position and transferring that thinking to the LR compression scenario.

  14. - S.A. -

    - S.A. - New Member

    Sizes for BFG's

    BF Goodrich All-Terr T/A KO
    Rim Widths 7.0-8.5
    Tread Depth 16
    Tread Width 9
    Diameter 31.3
    Max Load 3000
    Max PSI 65

    BF Goodrich All-Terr T/A KO
    Rim Widths 7.5-9.0
    Tread Depth 17
    Tread Width 9.2
    Diameter 32.9
    Max Load 3305
    Max PSI 65

    Goodrich All-Terr T/A KO
    Rim Widths 7.5-9.5
    Tread Depth 17
    Tread Width 11.6
    Diameter 33.5
    Max Load 3415
    Max PSI 65

    LT305/70R16D 118/115Q
    BF Goodrich Mud Terrain T/A KM
    Rim Widths 8.0-9.5
    Tread Depth 21
    Tread Width 12.2
    Diameter 33.1
    Max Load 2910
    Max PSI 50

    BF Goodrich All-Terr T/A KO
    Rim Widths 8.0-10.0
    Tread Depth 17
    Tread Width 12.1
    Diameter 34.7
    Max Load 3195

    check out the info on this websight..they are expensive though.


  15. MoJ

    MoJ Moderator

    Hadn't seen the 295/75 A/T before. B-Man, thanks for the info, sounds like they're only a problem when reaching for the outer limits of the 80? I've been ok with the 11.50 A/T's on my 91 (pretty serious wheelin) but they're only 32 inches tall. With the wider flares on my 94 I'm tempted to let the urge for form surpass the need for function and go for the wider tire (or tyre). BFG A/T would likely have less a chance of rubbing than the M/T? Make sense?
  16. merbesfield

    merbesfield SILVER Star

    Atlanta, GA
    which sizt tire did you go with? i go for tires tomorrow.
  17. NorCalDoug

    NorCalDoug problems solved daily... SILVER Star

    uhhhh...duh...Northern CA
    No idea what Moj went with...

    you're going for tires tomorrow?
    My suggestion is that you get a set of all-terrain or mud-terrains in a 285/75 R16 size.

    I have no idea who you are or how you plan on using your rig...but I think the 285s would be the safest suggestion.

    The 305/75 R16 would fit well enough with stock suspension, and would add about 3/4 inch width on each tire. This is seen as a benefit by many...I don't necessarily agree (but I'm a cheap bastard some times). You'll find the 305s will run about $20 to $25 more per tire than the 285s will -- $100 - $150 will buy quite a few adult beverages...

    So - without knowing anything about you I can definitely...without a doubt...suggest the 285 to you.

    ...but that's just my opinion...I could be wrong...
  18. MoJ

    MoJ Moderator

    Wow, old post, I can't even remember typing that. I ended up going with 305/70 BFG A/T and have been happy. I like the extra width but as Doug said the 285/75 is a great choice as well. If I was buying tires tommorow I would again go with the 305/70. If you look in the FAQ section you can see some pics of my 94 (before lift) with the 305's. I ran without a lift for some time, including off-road, and never had any problems. Here's a link:


  19. Mudshack

    Mudshack New Member

    Lee's Summit, MO (KC)
    I use this site all the time for the conversion - www.4lo.com

    They have like a dozen conversion programs. Just go to the Metric-to-English option across the top.

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