Truck tire sizes and general recommendations.

Discussion in 'Off Topic [BG]' started by two fingers, Jul 21, 2017.

  1. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
    Edit: See post #9 for updates please.

    So, we have experts on every dang thing else here. Why not tires?

    My stock truck tire size is 265/70/17. Crew cab full-size truck.

    I need tires.

    I will not jack the truck up....or level it.....or lower the rear as seems to be a weird trend right now. I just want to leave everything stock. But, I do think it would look better with a slightly taller tire on it. I can't find a simple explanation of how the ratios affect height. If I recall, the second number is something like height as a percentage of width or something like that?

    A link to a simple explanation would be great.

    Anyway, so let's say I want to go an inch or so taller. Nothing tremendous. Just a little taller. My truck has a big, sort of square, tire well. So clearance shouldn't be an issue. You think I could get away with...say....a 285/70/17? How much taller would that be than stock?

    Also, I'm a pavement gypsy. So any recommendations for a good highway truck tire would be great. We rarely get any snow. I rarely get into mud even on our farm. The paths are in good shape. But I travel to the mountains and beach a lot....on the pavemintz. Something that rides good and isn't too loud would be great. Budget isn't a big deal.

    Last edited: Jul 21, 2017
  2. Meyatch

    Meyatch Supporting Member

    Nov 25, 2007
    the first number is the width of the tire in millimeters, the second number is the height of the sidewall, as a percentage of that width. The third number is your rim diamter, in inches. So your stock tires are (265*0.70*2) mm, plus 17" = 31.6" tall. Changing the height of your tires will screw up your speedometer. If you are going taller, that's just something you'll have to live with. I've used this calculator before, to go wider, without screwing up my speedometer.
    Tire size calculator
    elgecko likes this.
  3. BasturdBlaster


    Feb 19, 2012
    Crandon WI
    285 will be wider and taller though not by much for either. I think you should be looking to change the mid number going up like "75" vs "70".

    If you take your truck in to have the tires put on, you may have trouble finding a shop that will install anything but the stock size. Liability or something I suppose.

    If that is the case, you need to bring in the wheels already taken off the truck and then they will usually install them.
    two fingers likes this.
  4. Meyatch

    Meyatch Supporting Member

    Nov 25, 2007
    I missed the second part of your question. According to the calculator I linked, they would be an inch taller, and 3.5% bigger circumference (which is what screws up your speedometer)

    Most likely there is a forum for your truck, where guys with experience will tell you what size tires they are running, without rubbing. You can also go to various online tire sites, and there's a decent chance a version of your truck came with bigger tires, and would therefore fit on your truck, probably a version with bigger rims, and wider tires.
    two fingers likes this.
  5. hbarcat

    hbarcat Supporting Member

    Aug 24, 2006
    Rochelle, Illinois
    If you want to get "taller" tires simply for looks, then the only sensible way to do this without compromising your handling or longevity of parts is to go with wider rims and tires.

    Shell out the cash for 18" rims and determine what tires will fit. Besides making your speedometer off, using a larger tire will result in sluggish acceleration. Also make sure the wheel offset is correct and that the larger tires will fit without rubbing or hitting when driving on rough roads.

    Meyatch suggested you find a forum of enthusiasts for your truck and see what they recommend. I'd follow that advice.
    Last edited: Jul 21, 2017
    two fingers likes this.
  6. Pilgrim

    Pilgrim Supporting Member

    Remember that if you change the diameter of the tires, you introduce speedometer error. I personally think that's a pretty bad idea. Changing the width can also affect tire diameter, so it's good to check.

    One of my favorite references is to go to Tire Rack online and use their specs on tires to compare diameter of tires and revolutions per mile. If you choose a replacement that's as close to the OEM tire diameter as possible, your speedometer will still be accurate.

    Example: BFGoodrich Advantage T/A Sport (H- or V-Speed Rated)
    two fingers likes this.
  7. elgecko


    Apr 30, 2007
    Anasleim, CA
    On some vehicles, you can correct tire size change speedo errors at the ECU. I couldn't on my truck but I've been driving it so long, I automatically make the correction in my head.

    EDIT: I'll add that people are making a bigger deal of speedo error than it actually is. If you go up an inch from 32" to 33" tires, that's a 3% difference. That means if your speedo reads 50mph, you're actually going 51.6mph.
    Last edited: Jul 21, 2017
    two fingers likes this.
  8. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
    OK, thanks so far.

    I used a calculator I found on Discount Tire Direct and it still didn't answer my questions fully. (I mainly wanted to know how that tire would work on my truck with regard to rubbing during turning and whatnot.) I called the number on the web site and got what I needed. I started describing my truck and my situation to "the guy". He was rather cheerful, but did interrupt me and said "You can go up to thirty threes without rubbing man." There was a long pause because I thought there would be more. So I asked for clarification being that I had the height, width and circumference right in front of me. He said the height difference and width difference was good to go and that it wouldn't rub the tire well even on sharp turns.

    For reference the differences are as follows

    265/70/17 to 285/70/17

    Height difference - 1.1" (from 31.6" to 32.7")
    Width difference - .79"
    Speed at speedometer readings 67.27@65mph - 56.92@55mph - 46.57@45 (negligible in my world)

    Man, the interwebz really is amazing.

    So I guess the question is this. Are there really any other things to consider other than clearance in the tire well and speedometer compensation? Getting in and out will only be affected by a half inch. So the fingers girls shouldn't even notice a difference mounting and dismounting the back seat.
  9. Pilgrim

    Pilgrim Supporting Member

    If it's not rubbing and error is minimal, then there are two things left.

    First is load rating. If your truck is used for actual hauling and carrying work loads, make sure that you choose a tire with sufficient load rating for the wood/gravel/pig iron you carry. Also true if you put a camper in the back for vacations or hunting trips.

    If the truck is a passenger vehicle that occasionally carries furniture or other light loads, then a passenger tire load rating will be OK.

    The other factor is is handling. Tires make the most difference in your vehicle's handling of any change short of suspension modifications. On a truck, that's usually not a major factor, but this is another reason I hit Discount tire and Tire Rack to check reviews on handling. You can also get ratings on wet, dry and snow traction. If you buy an all-season tire, you probably want good performance in snow if you'er in the northern tier.
    two fingers likes this.
  10. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA

    Yeah regular consumer use. Camper shell on back. The occasional two kayaks on top. Bass/PA gear. A regular utility trailer with pine straw or yard debris, etc. Luggage for Her Higness and the fingers girls. It hauls the ever loving crap out of groceries. :D

    The one I'm looking at gets great traction ratings, quiet ratings, load ratings and "meh" off-road ratings.....which is pretty much where I am. Supposedly it does great in sand, rocks and snow, but doesn't "clean itself" well enough for deep mud. I don't do deep mud. And I rarely do sand and snow. There are zero rock climbing trips in this truck's future.
  11. ZenG

    ZenG Guest

    Make sure you know what load rating is required for your truck.

    You can usually find other tires that will fit. But that doesn't mean they are correct for load.

    Also the rim width is important. You need to know the width of the rims you will use. Some tires are finicky on rim width. For example: You could them on a 7 inch rim but you could not use them on a 7.5 inch rim.

    Remember...the higher the tire sidewall, the more variation there is laterally when cornering.
  12. MJ5150

    MJ5150 Moderator Staff Member Gold Supporting Member

    Apr 12, 2001
    Olympia, WA
    I dropped the rear end in my Ram to level it out, then upgraded to the stock 20's from the 17's it came with.
    That made it look a bit taller.

    Last edited: Jul 21, 2017
  13. Gorn

    Gorn Supporting Member

    Dec 15, 2011
    Queens, NY
    Just out of curiosity, what would happen if you put tiny tires on a big truck? Like Corolla tires and rims and all that on one of those giant pickups? Would it be able to drive at all?
  14. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
    Sure. Just more slowly. Remember when lowering vehicles was all the rage? They would lower even full-size truck down to the ground and put tiny tires on them. It kind of defeated the purpose of having a truck (in my view) but it still rolled.
  15. If this was my truck (which it's not) and I wanted a bit taller tire , the easiest way to go would simply be going to a 265 75 17 tire. This wouldn't be much taller , the speedo difference would be negligible , with it being a truck , the chances of any rubbing due to a slightly taller tire would be non existent and it shouldn't require wider rims as the width of the tire would be the same. Gas mileage would get a bit better , acceleration would get a bit slower but I don't think either would really be noticeable. Not sure if a 275 by anything would require wider rims but I'm pretty sure that a 285 by anything would need at least a 1" wider rim. If you want to go with a larger tire and new rims , the sky's the limit but this would get pretty expensive. Yup , 265 75 17 it is.:thumbsup:
  16. two fingers

    two fingers Opinionated blowhard. But not mad about it. Inactive

    Feb 7, 2005
    Eastern NC USA
    I'm not arguing. I really don't know.

    Why would a tire that is well under an inch wider require "at least a 1" wider rim". Check out post #9 to see the difference in tire width between a 265/70/17 and a 285/70/17.

    Thanks for the advice.
  17. jraskell

    jraskell Guest

    Mar 27, 2017
    New Hampshire
    Don't know what brand/model tire you're looking at, but one model I looked at on Tire Rack showed the 265/70 tire supporting wheel widths 7"-9" with the measuring width being 8" and the 285/70 supporting wheel widths 7.5"-9" with the measuring width being 8.5"

    As long as your wheels aren't only 7" wide, the 285s will be fine. If your wheels are only 7" wide, the 285s will still be mountable, but your handling and tire wear will be negatively impacted, and you'll probably have trouble finding a shop willing to mount and balance them.
    two fingers likes this.
  18. Mike N

    Mike N Missing the old TB Staff Member Gold Supporting Member

    Jan 28, 2001
    Spencerport, New York
    OP - What year/make/model truck are we dealing with?

  19. Not totally sure it would. I do know that on my old Firebird , it came with two different size tires (smaller on the front) and the size difference was two sizes (don't remember the specifics) and that the rear rims were an inch wider. As far as I know , they were the original stock rims. I did buy the car used so it could have had stuff changed out but the rims appear to be stock. Might not be the case for truck tires.
    two fingers likes this.