1. Welcome to Jeeps.net!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Jeep discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Jeep owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Tires & odometer mileage

Discussion in 'Wheels & Tires' started by rapracing, May 9, 2017.

  1. May 9, 2017 at 2:33 PM
    #1
    rapracing

    rapracing [OP] Member

    Joined:
    Apr 24, 2017
    Member:
    #1386
    Messages:
    14
    Gender:
    Male
    Pretty sure I know the answer but would like it confirmed. If I take stock tires off and put 35's on and do not change the speedo gear

    A. What happens to registered speed, am I going faster or slower than indicated?

    B. What about mileage accumulation on the Jeep, does it show more or less than is actually being put on the drive train?
     
  2. May 9, 2017 at 3:44 PM
    #2
    aggrex

    aggrex Well-Known Member

    Joined:
    Sep 12, 2016
    Member:
    #203
    Messages:
    3,913
    DE
    Vehicle:
    Backcountry '16
    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    Larger tire will have less revs per mile = Your speedometer will read lower than actual speed
     
    Last edited: May 9, 2017
    phonedrn8 and JKBob 25 like this.
  3. May 9, 2017 at 5:46 PM
    #3
    Rc Jeep

    Rc Jeep Well-Known Member

    Joined:
    Sep 8, 2016
    Member:
    #190
    Messages:
    465
    Gender:
    Male
    First Name:
    Ryan
    Vehicle:
    '16 Rubicon
    Evo mfg front coil overs Evo mfg rear coil overs Jks drag link flip Je reel 1310 front & rear driveshafts 37" Nitto trail grapplers 17x9 atx slabs Evo mfg quarter pounder w/stinger Evo mfg rear fascia w/ d ring mounts
    It will show less miles on the odometer and your speedo will show less than your actual speed.
     
    JKBob 25 likes this.
  4. May 9, 2017 at 6:39 PM
    #4
    JKBob 25

    JKBob 25 Well-Known Member

    Joined:
    Mar 22, 2017
    Member:
    #1197
    Messages:
    3,748
    Gender:
    Male
    First Name:
    Bob
    Jersey Shore, NJ
    Vehicle:
    2016 JK Wrangler Sport
    2" Superlift kit. 315/ 70/17.
    Your tranny will change gears at different slower speeds too which will make your Jeep very sluggish.
    Why not just buy a reprogrammer and set it up for the 35s.
     
    Last edited: May 9, 2017
  5. May 9, 2017 at 6:50 PM
    #5
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    2,018
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Depending on the set up, older trannys change gears based on vacuum and rpms. Newer trannys are based on rpms and other electrical inputs. They all feel sluggish because the power to output force (torque) ratio at the wheels has been diminished, hence the desire and/or need to regear. Everybody above is correct. Your speedometer will be displaying slower than you are actually driving, and you will log fewer miles than you have actually driven.
     
    aggrex and JKBob 25 like this.
  6. May 9, 2017 at 9:05 PM
    #6
    rapracing

    rapracing [OP] Member

    Joined:
    Apr 24, 2017
    Member:
    #1386
    Messages:
    14
    Gender:
    Male
    It's an '06. Standard Transmission. The guy selling claimed it had been ran for some time with the 35's on it without changing the gear. That has been corrected now. He was telling me it would have less miles than indicated on the Speed O because of that.

    Running that through my thick skull it didn't compute so I thought I'd come here and ask. My thoughts were it would show I was moving slower than I actually was and that it would also show less milage than was actually being accumulated.

    Thanks for verifying
     
  7. May 10, 2017 at 6:38 AM
    #7
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    2,018
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    So depending on which model you are talking about they come with either 29 -32 in tires. Lets say it was 31s The circumference of a circle is 2TTr 31s circumference is 2x3.14x15.5= 97.65in and the 35s circumference is 2x3.14x17.5= 109.9in To find the percentage difference divide the bigger tire into the smaller tire. 97.65/109.9= .888535 or 89% What this means is for every 100miles driven with 35s you can add another 11miles onto the odometer. 1000 miles add 110miles to the odometer. 100000 miles add 11000 miles to the odometer. Really not that much difference on a 10 year old vehicle. IF youre getting a GOOD deal, I wouldn't let that sway your decision.
     
    JKBob 25, aggrex and Bob like this.
  8. May 11, 2017 at 2:18 PM
    #8
    JEEP # 5

    JEEP # 5 Well-Known Member

    Joined:
    Jan 25, 2017
    Member:
    #871
    Messages:
    82
    Gender:
    Male
    First Name:
    MARK
    Vehicle:
    2014 BLACK & GREY
    Has 35 X 17 X 12 LT & a 4" RC lift, Smitty Bilt Nerf bars 3" tube
    Offgrid, you are ONGRID when it comes to numbers!! Well said!!
     
    JKBob 25 likes this.
  9. Aug 31, 2017 at 8:35 PM
    #9
    Aletani

    Aletani Well-Known Member

    Joined:
    Aug 28, 2017
    Member:
    #1823
    Messages:
    108
    Gender:
    Female
    Augusta, GA
    Vehicle:
    '09 JK
    JKS 2.5" Lift
    .... Driving down the highway I was following hubby and going 60mph, ten under the speed limit. He ended up calling me soon after and I was like, babe, I can drive 70mph, its not a big deal... He was like, I'm going 78!!!


    So I'm thinking when the previous owner put on the 35s they didn't adjust the speedometer... Is that the only thing that needs checked and adjusted? What does that entail?


    95% of my manual driving experience is from growing up dirt bike riding, but I feel like the JK shifts well and everything, but could adjusting the tire size require regearing? What sort of things should I be noticing if it is needed?


    Any feedback and suggestions is very welcome. Thanks!
     
    JKBob 25 likes this.
  10. Sep 1, 2017 at 7:37 AM
    #10
    Prerunner1982

    Prerunner1982 Well-Known Member

    Joined:
    Aug 4, 2017
    Member:
    #1745
    Messages:
    1,274
    Gender:
    Male
    First Name:
    Jon
    Vehicle:
    93 XJ 2 door
    A change in tire size if large enough should require a regearing. A small change in tire size and you can get away without changing gears. A large difference in tire size and stock gears may be ok on flat roads but you may notice that you have to down shift a lot of get up hills or that your Jeep is sluggish against a headwind as it doesn't have the torque that it once did.

    If you aren't noticing any sluggishness I would check to see what gear ratio you have, it may have been changed already.
    You can jack up the rear end and rotate the tire one time while counting how many times the driveshaft turns. A little over 4 rotations of the driveshaft would be 4.10/4.11 gear ratio, three and 3/4 turns would be 3.73 ratio, a little over four and a half turns would be 4.55.
     
    JKBob 25 and Aletani like this.
  11. Sep 1, 2017 at 8:05 AM
    #11
    Aletani

    Aletani Well-Known Member

    Joined:
    Aug 28, 2017
    Member:
    #1823
    Messages:
    108
    Gender:
    Female
    Augusta, GA
    Vehicle:
    '09 JK
    JKS 2.5" Lift
    Thanks! I'll have to test out the driveshaft turns. It is kind of sluggish on hills and I have poor torque in first for our steep grade driveway... Kinda worried that it'll need the regear. I'm trying to get into a local club to hopefully get some help without breaking the bank...
     
  12. Sep 1, 2017 at 8:14 AM
    #12
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
    Oct 3, 2016
    Member:
    #317
    Messages:
    2,018
    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    If I'm not mistaken you said you have 373 gears. That will,handle the 35s no problem. If you are happy with how it drives now, just by a programmer like a super chips or hypertec programmer, plug it in and adjust the computer for tire size. As prerunner said regearing helps, but in your case I don't believe it absolutely necessary. It is something you can do when you have the extra money. Regearing will give you a little more "Umph" from a stop and when passing somebody.
     
    JKBob 25, aggrex and Aletani like this.
  13. Sep 1, 2017 at 8:17 AM
    #13
    Aletani

    Aletani Well-Known Member

    Joined:
    Aug 28, 2017
    Member:
    #1823
    Messages:
    108
    Gender:
    Female
    Augusta, GA
    Vehicle:
    '09 JK
    JKS 2.5" Lift
    Ok. Thank you. (yes, 3.73 with the 35"s) I bet hubby would like to avoid the cost of regear atm, so hopefully reprogramming will help a bit, if only to display accurate speed. I think ideally I'd like to regear to 4.11 or 4.56, but that'll have to be down the road.

    Flashcal or take it to a dealer?
     
    JKBob 25 likes this.
  14. Sep 1, 2017 at 11:11 AM
    #14
    Rc Jeep

    Rc Jeep Well-Known Member

    Joined:
    Sep 8, 2016
    Member:
    #190
    Messages:
    465
    Gender:
    Male
    First Name:
    Ryan
    Vehicle:
    '16 Rubicon
    Evo mfg front coil overs Evo mfg rear coil overs Jks drag link flip Je reel 1310 front & rear driveshafts 37" Nitto trail grapplers 17x9 atx slabs Evo mfg quarter pounder w/stinger Evo mfg rear fascia w/ d ring mounts
    3.73 gears work on 35s but it's sluggish. The manual trans helps a bit vs an automatic. I would suggest 4.56 when you do eventually regear.

    I have 4.10 on 37s for about a year now. It's not ideal but works.
     
    OFFGRID, JKBob 25 and Aletani like this.
  15. Sep 1, 2017 at 11:28 AM
    #15
    Aletani

    Aletani Well-Known Member

    Joined:
    Aug 28, 2017
    Member:
    #1823
    Messages:
    108
    Gender:
    Female
    Augusta, GA
    Vehicle:
    '09 JK
    JKS 2.5" Lift
    Yeah. 4.56 sounds like what I'd want for it.
     
    JKBob 25 likes this.
  16. Sep 1, 2017 at 2:11 PM
    #16
    JEEP # 5

    JEEP # 5 Well-Known Member

    Joined:
    Jan 25, 2017
    Member:
    #871
    Messages:
    82
    Gender:
    Male
    First Name:
    MARK
    Vehicle:
    2014 BLACK & GREY
    Has 35 X 17 X 12 LT & a 4" RC lift, Smitty Bilt Nerf bars 3" tube
    Yes, exactly what OffGrid said. Get the programmer so your computer can know what your tire size is currently. That will match your Speedo up to real speed or very close. Test the real speed up against your GPS. You can also tell your computer if you plan to Tow something, Change tire height, different elevations, many options and Super Chips is menu driven and very easy to use designed to specifically work with Jeeps. It in the menu choice of vehicles..

    This is exactly what I did with my 2014 JK V-6 with 35" Tires. I pull my boat all the time. Cruz 95 on the way flats with nothing behind. Tall tires will allow for that but takes away out of the hole a little just like OFFGRID and many pothers have said.
     
    JKBob 25 and OFFGRID like this.
  17. Sep 1, 2017 at 2:16 PM
    #17
    JEEP # 5

    JEEP # 5 Well-Known Member

    Joined:
    Jan 25, 2017
    Member:
    #871
    Messages:
    82
    Gender:
    Male
    First Name:
    MARK
    Vehicle:
    2014 BLACK & GREY
    Has 35 X 17 X 12 LT & a 4" RC lift, Smitty Bilt Nerf bars 3" tube
    One more thing @ rapracing My wife has the 2003 Rubicon, the Superchips programmer fit and I adjusted her tire height 33" and speedo to read properly now. So it will reprogram yours just fine.
     
    JKBob 25 likes this.
  18. Sep 1, 2017 at 2:21 PM
    #18
    aggrex

    aggrex Well-Known Member

    Joined:
    Sep 12, 2016
    Member:
    #203
    Messages:
    3,913
    DE
    Vehicle:
    Backcountry '16
    Tuffy>AEV>TTO>JW>STech>EVOcage>MagnaFlow>SpiderTrax>RockHard>TF>SpringTail>67design>Bolt>GPCA>Curt>
    Just get a programmer..its ez. AEV procal or Superchips FlashCal F5
     
    JKBob 25 and JEEP # 5 like this.
  19. Sep 1, 2017 at 2:23 PM
    #19
    JEEP # 5

    JEEP # 5 Well-Known Member

    Joined:
    Jan 25, 2017
    Member:
    #871
    Messages:
    82
    Gender:
    Male
    First Name:
    MARK
    Vehicle:
    2014 BLACK & GREY
    Has 35 X 17 X 12 LT & a 4" RC lift, Smitty Bilt Nerf bars 3" tube
    FLASHCAL - SUPERCHIPS, I vote Super Chips
     
    JKBob 25 and aggrex like this.
  20. Sep 1, 2017 at 2:38 PM
    #20
    Aletani

    Aletani Well-Known Member

    Joined:
    Aug 28, 2017
    Member:
    #1823
    Messages:
    108
    Gender:
    Female
    Augusta, GA
    Vehicle:
    '09 JK
    JKS 2.5" Lift
    Thanks guys! I found a highly reputable jeep modder and mechanic who is going to take a look at it and assess the ratio and then hopefully just reprogram for me.

    I really appreciate all the info. Its very helpful!
     
    JKBob 25 likes this.
To Top