General Tire height and effect on AWD

Discussion in '4th Generation (2013-2017)' started by PanayiotisPal, Monday 19th Sep, 2016.

  1. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    Changing the tire size from 225 60 R18 to 235 60 R18, gives 1cm longer tire height (or 0.5 cm higher ground clearance).

    What will the AWD effect be from this change?? Will it behave the same??

    Yesterday I changed my old tires to 225 60 R18 (same as original) but my mechanic (he sells tires too) told me that I also had the option of 235 60 R18 if I wanted to so I have this query (at least for the next time).
     
    Loading...
  2. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    Next 4 tire change will be 235 60 R18. My understanding is that apart from the speedometer reading and fuel consumption the AWD operation is not affected.
     
    Loading...
  3. MikeM-271048 Senior Member ★ ★ ☆ ☆ ☆

    Italy Mike Bruno
    199
    83
    When I got my "libretto" for the CR-V, it gave the dimensions that have been approved for the 4th Generation facelift in Italy. Although this is, of course, an Italian national approval, but I would be a bit surprised if there were no equivalent approval system in Cyprus. FWIW, the sizes allowed are:
    • As supplied: 225/60 R18 96H
    • 225/65 R17 96H
    • 245/45 R17 96H
    Good luck with your research!
     
    Loading...
    PanayiotisPal likes this.
  4. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    The manufacturer recommends tire sizes that will not have an impact on speedometer accuracy. This is the main idea behind the owner manual and the recommended tire sizes as I understand it. I am not sure if legally this is allowed, e.g. when cruising at 100km the actual speed is 105km due to higher tire size used..

    Another questions that pops on my mind is the following:
    Is there a setting on the HDS Honda diagnostic that takes into account the tire size?? If yes then I will also have to change this value.
     
    Last edited: Monday 19th Sep, 2016
    Loading...
  5. MikeM-271048 Senior Member ★ ★ ☆ ☆ ☆

    Italy Mike Bruno
    199
    83
    The "libretto" is not the manual. It is the registration document, like a French carte grise or (in the old days) a UK logbook. That's what I meant about government approval for the tyre sizes it specifies.
     
    Loading...
  6. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    I guess this is a modification from the manufacturer specs. Is there an allowable % in tire height increase e.g. in the UK?? if not then I will be illegal and probably 235 55 R18 is the correct upgrade, which will give same speedometer accuracy reading.
     
    Loading...
  7. MikeM-271048 Senior Member ★ ★ ☆ ☆ ☆

    Italy Mike Bruno
    199
    83
    As our models are different, I can't say whether the size you are proposing will make you illegal. What I remember from school is that a small increase in diameter makes a multiplier effect on the tyre diameter. Going from 225 to 235 will increase the tyre diameter by 235/225, or 9.5%. All other things (I imagine, tyre pressure most of all) being equal, this should increase your speed by the same percentage. Which pretty much kills off any safety margin the local speed cops may give you.
     
    Loading...
    PanayiotisPal likes this.
  8. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    Actually the speedometer error is only -1.7%, and the tyre diameter increase is +1.7% only.
    https://tiresize.com/comparison/

    So the speedometer error of 2km when speeding 100km is not a lot and should not create a problem..

    Here are the calcs showing that tire is 12mm higher.

    The actual width increase is (235-225)/225=4.5%
    Tire sidewall height = 60 x225 =135 mm
    Tire sidewall height = 60 x 235 = 141 mm

    Tire sidewall increase = (141-135)/135 = 4.5%

    18 inch rim = 457 mm
    Total height of 225 = 457 + 2 x 135 = 727
    Total height of 235 =457 + 2 x 141 = 739

    Total height difference is 12 mm.
    or Ground clearance increase by 6 mm.

    Advantages
    I guess the tire will last longer due to less revolutions at the same distance, and ride would be smoother due to tire having higher sidewall length, and probably much better for offroad use (vibrations are absorbed much better). It will also have less temperature and as already discussed will increase the ground clearance of CR-V by 6 mm (from 165mm to 171 mm).

    Knowing the above information it is worth to change to 235 60 R18 tires unless there is a reason we should not.
     
    Last edited: Tuesday 20th Sep, 2016
    Loading...
  9. chunkymonkey Senior Member ★ ★ ☆ ☆ ☆

    United Kingdom Gary Lincs
    203
    108
    Insurance! Give them any wriggle room and thats it they won't pay up. The first thing the Police do is check tyres including tread depth pressure and size its all noted and forms part of an investigation following a serious accident. Trust me I know what I am talking about as I am Emergency services and one of my mates is the senior traffic collision investigating police officer in our county.

    Sent from my SM-G920F using Tapatalk
     
    Loading...
    Zebster and PanayiotisPal like this.
  10. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    Do you think that this tire profile is less safe??? In the court I can prove that is more safe. I agree that insurance will be a problem but there should be court decisions on this in favor of the driver/insured person. If not then there is always the first time. Just expressing an opposite view, though I am agreeing with your opinion too.
     
    Loading...
  11. Beefy Expert Advisor ★ ★ ★ ★ ★

    United Kingdom Stoke
    1,120
    690
    1
    As it is not something Honda originally spec for the car nobody can say with any certainty. It may effect AWD and tyre deflation. Also ABS/VSA as they all rely on the rolling radius of the tyre. Honda expect for each tyre size a nominal side wall height. Maybe it will adversely effect things. Maybe not. But nobody can say for sure
     
    Loading...
    legend-ary and PanayiotisPal like this.
  12. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    :Smile: Beefy I am now more puzzled. Thanks for pin pointing this. Do you know if there is an HDS setting for tire size?? for correcting the issues you described??
     
    Loading...
  13. chunkymonkey Senior Member ★ ★ ☆ ☆ ☆

    United Kingdom Gary Lincs
    203
    108
    I am mo legal eagle I am just stating what I know, having seen what happens in court and being involved with investigate evidence if you feel capable and competent to prove the safety good luck to you but based on experience its not a place I would go! Besides if you caused an accident your insurance would be invalid had you not claimed the modification and therfore by virtue are breaking the law with no valid insurance. Basically your nuts are in a vice so to speak.

    Sent from my SM-G920F using Tapatalk
     
    Loading...
    PanayiotisPal likes this.
  14. Zebster Expert Advisor ★ ★ ★ ★ ★

    United Kingdom .
    2,559
    1,247
    1
    It doesn't matter one bit if you can prove this modification is 'safer'. It's a modification and insurance companies always ask to be told about modifications...
     
    Loading...
  15. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    This is what I am trying to find out. If I can satisfy Beefy's questions regarding the ABS/VSA/tire deflation correct operation,, by feeding the tire size in Honda software settings, using the Honda Diagnostic Software (if this option exists) and getting a certification for this modification, then I can prove to insurance or local authorities that it is safe/safer to use, in order to get their permission too.
     
    Loading...
  16. chunkymonkey Senior Member ★ ★ ☆ ☆ ☆

    United Kingdom Gary Lincs
    203
    108
    Good luck!!!!!!

    Sent from my SM-G920F using Tapatalk
     
    Loading...
    PanayiotisPal likes this.
  17. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    I will need it. :Smile: Thanks.

    I guess no one with CR-V AWD 4th Generation has carried out this tire modification as it is troublesome. I need a mods advisor :Smile: but a honda diagnostic software expert will do too. I need to find out if there is an option to modify the tire size in the software settings of CR-V.
     
    Last edited: Tuesday 20th Sep, 2016
    Loading...
  18. SpeedyGee Administrator Staff Team

    England Speedy Birmingham
    14,999
    5,595
    4
    I would doubt that HDS has any such options.
     
    Loading...
    PanayiotisPal likes this.
  19. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    If HDS does not have an option, I cannot prove anything. There is an hack on the CR-V EX version of the navigation/display that lets you change some settings, where you see the yaw rotation speed. I don't remember the options displayed. I have to do some research if such an option exists.
     
    Loading...
  20. PanayiotisPal Top Contributor ★ ★ ★ ★ ☆

    Cyprus Panos Paliometocho
    562
    107
    4
    In USA it is acceptable. Look at the table. 235 60 R18 is an option on 2.4 engine model 2014

    Honda CR-V 2014 - Wheel & Tire Sizes, PCD, Offset and Rims specs - Wheel-Size.com





    Tire

    Rim

    PCD
    225/65R17 6.5Jx17 ET505x114.3 2.3
    225/60R18 7Jx18 ET505x114.3 2.3
    235/60R18 7Jx18 ET505x114.3 2.3
    245/50R19 7.5Jx19 ET485x114.3 2.5
    255/45R20 8Jx20 ET455x114.3 2.6
    - - - Updated - - -
    but not on 2.0i. but It should be the same.
    - - - Updated - - -
    For 2.0i it gives 235/65R17 whereas on 2.4i it gives 235/60R18. I wonder why.
    - - - Updated - - -
    though they have the same tire height, so it should be ok
    - - - Updated - - -
    I can make use of the USA CR-V owners manual in the court :Smile:
    - - - Updated - - -
    Next tire change will be 235 60 R18.
     
    Loading...