Results 1 to 4 of 4
  1. #1
    Active Member
    Join Date
    Jan 2018
    Location
    Australia
    Posts
    146
    Spyder Garage
    0

    Default The 'good oil' - What diference between front and rear stock F3 tyres (tires)

    I have to admit I've been looking for quite some time and wanting to throw on a descent set of aftermarket wider front wheels …. And by saying 'some time' , I mean way better than a year or more.

    Almost every other day I am hearing or reading of where people are being pessimistic about 'nanny' supposedly sensing a differential between the front and rear wheel sensors on the F3's .... Its either that or how Can Am Spyder's supposedly can't be put on a dyno.

    Well I decided to work things out rather than just looking and listening anymore …

    I've particularly noted a few of the nice looking custom bikes always running about 20" wheels. I then thought, the obvious way to achieve this is to change all 3 wheels. Then I thought, I wonder how far could I go up in size on a change to the front wheels only, without changing the back wheel, but working between profile sizes of the interchange rims.

    Eventually as a natural progression of this I then thought … I wonder if there is any differential between the stock front and back wheels in total as the stock factory bike sits at the point of delivery … So I wrote down the wheel and tyre sizes front and rear, then went to 'wheel-size. com' who have a great tool for comparing various proposed rim and tyre size interchanges. If you can find better, I'd be amazed.

    Anyway … here amazingly are the results …. The stock F3's (mine is a 2017 F3-T) on the front run a 165 55 R15 tyre on a 5" rim …. so I dialled that in (forget about the quoted MC part as that is only a rating) …. You will find the considered average tyre has a circumference of 1767mm, a diameter of 563mm and by their conversion has 525 revolutions per kilometre …. The rear runs a 225 50 R15 tyre with a 7" rim … so once again when I dialled that in. They have a circumference of 1904mm, a diameter of 606mm and does 515 revolutions per kilometre.

    Anyone notice anything here …. straight away the stock front and back wheels have a 7% differential in diameter and an 8% difference in revolutions per kilometre (or mile - its a constant so distance will not change the outcome)

    But wait a minute … I am continually hearing by many how they are worried about any differences between front and back wheel inputs because of the 'nanny' …. hmm … so lets push this a bit more ….

    Being an old electronics based tradesman (avionics engineer on aircraft) … I definitely know that I will trust my GPS every day of the week long before any indicating speedo. Via my GPS it always reads when I am doing exactly 100 KPH (here in Australia), (or in the USA's case MPH) my stock speedo setting reads about 102 kilometres an hour. …. Wait a minute there's another differential …

    You see by legislation, doesn't matter where we are all based world wide, every country has legislated its OK for our vehicles to be indicating to high (in other words we are actually going slower than indicated) rather than too low (which conversely mean we would be travelling above the posted speed for the area). …. That way supposedly we are never speeding. Whether that's 55 or 60 MPH in the US or 80 or 100 KPH here in Australia ….

    So where am I going here … By showing the GPS speedo indications I know straight away I am actually doing about 2% low of what is actually happening and being indicated. If that's the case, if I want to correct my speedo I have one of two options … 1) … Increase the profile of my tyre sensing wheel (rear wheel on my Spyder F3-T) or ….. 2) … (and I didn't realise this until I got right into this) … If I increase the tyres width just ever so slightly, I will actually increase the profile sizing as well, and still keep the same profile. My tyres side wall profile will actually change up very slightly ….

    So there they are! In this case, for a true speed option indication (your call) you can either increase the profile (+1 size), or go up to the next tyres width ….. For me here …. its only one or the other not both …. Going up in profile approximately doubles the change that you will get from just changing the width one size …. for example a one change size up from a 225mm tyre to a 235mm tyre, you will go up in wall profile size about 1/2" total as compared to 1" (if you were to go up one profile step instead) …

    I'm now 66 years old and always love learning something new ….

    The next phase in this …. I have (finally) worked out how I can have a 5 stud adapter made for the front wheels, enabling going to 19" or even 20" wheels and using all of the new 5 studs with no interference between the original 3 stud pattern of the Spyder ….. Then run those and still keep the same rear 15" wheel sizing …. amazing … loving the challenge …. If I wanted to be anal, I would also change the rear tyre width from the stock 225/50R15 to a 23550R15 to get that exact speedo reading correction I have just been rabbitting on so much about ...…. Cheers

    Just to prove I am not full of BS, very shortly when I do this I will post photos of the same … (PS small editing note … I've yet to delve into the realms of dyno-ing)
    Last edited by fatenhappy; 06-09-2018 at 04:04 AM.

  2. #2
    Very Active Member
    Join Date
    Nov 2016
    Location
    Upstate NY
    Posts
    754
    Spyder Garage
    2

    Default

    You can buy the 5 lug adapters on ebay. No problem going to a larger wheel. Width wont matter either, as long as it fits. The nanny wont care as long as you keep it within reason. 18 inch front wheels with a 35 or 40 series profile should be fine. Heck, the General rear tire I put on my spyder is quite a bit larger in rolling diameter than stock and doesnt cause any problems with the nanny. It does rub if I hit a big bump though.
    My rear tire is about 5% larger than stock with about 44 revs per mile less than stock. I think as a general rule, if you keep the difference less than 10%, you will be ok. I dont see anything in the B.U.D.S. program that I can change to fix the problem if the nanny doesn't like it. Maybe someone with more advanced knowledge of B.U.D.S. knows a way to correct for tire size.

    I did notice that all of the spyders with large custom wheels seem to be RS's. Probably because there is room for a larger rear tire. If the front tires you use are 10% larger rolling than stock, then do the same with the rear(10% larger). I did not see any photos of spyders with large front wheels running the stock rear tire size. Maybe because of nanny issues.
    Last edited by Joel The Biker; 06-09-2018 at 07:47 AM.
    2021 Sea to Sky RT , Highland green

  3. #3
    Very Active Member Highwayman2013's Avatar
    Join Date
    Nov 2012
    Location
    North Las Vegas, NV
    Posts
    4,561
    Spyder Garage
    1

    Default

    Yep we learned that going from the stock rear size to a 215/60/15 fixes speedo error.
    2016 F3 Limited
    2019 Ryker Rally
    2014 Suzuki V Strom 650
    2020 CSC TT 250
    2016 F 3 Limited , Vegas White

  4. #4
    Active Member
    Join Date
    Jan 2018
    Location
    mondovi wi
    Posts
    35
    Spyder Garage
    0

    Default rear tire i did go to 235 tire love it

    Quote Originally Posted by fatenhappy View Post
    I have to admit I've been looking for quite some time and wanting to throw on a descent set of aftermarket wider front wheels …. And by saying 'some time' , I mean way better than a year or more.

    Almost every other day I am hearing or reading of where people are being pessimistic about 'nanny' supposedly sensing a differential between the front and rear wheel sensors on the F3's .... Its either that or how Can Am Spyder's supposedly can't be put on a dyno.

    Well I decided to work things out rather than just looking and listening anymore …

    I've particularly noted a few of the nice looking custom bikes always running about 20" wheels. I then thought, the obvious way to achieve this is to change all 3 wheels. Then I thought, I wonder how far could I go up in size on a change to the front wheels only, without changing the back wheel, but working between profile sizes of the interchange rims.

    Eventually as a natural progression of this I then thought … I wonder if there is any differential between the stock front and back wheels in total as the stock factory bike sits at the point of delivery … So I wrote down the wheel and tyre sizes front and rear, then went to 'wheel-size. com' who have a great tool for comparing various proposed rim and tyre size interchanges. If you can find better, I'd be amazed.

    Anyway … here amazingly are the results …. The stock F3's (mine is a 2017 F3-T) on the front run a 165 55 R15 tyre on a 5" rim …. so I dialled that in (forget about the quoted MC part as that is only a rating) …. You will find the considered average tyre has a circumference of 1767mm, a diameter of 563mm and by their conversion has 525 revolutions per kilometre …. The rear runs a 225 50 R15 tyre with a 7" rim … so once again when I dialled that in. They have a circumference of 1904mm, a diameter of 606mm and does 515 revolutions per kilometre.

    Anyone notice anything here …. straight away the stock front and back wheels have a 7% differential in diameter and an 8% difference in revolutions per kilometre (or mile - its a constant so distance will not change the outcome)

    But wait a minute … I am continually hearing by many how they are worried about any differences between front and back wheel inputs because of the 'nanny' …. hmm … so lets push this a bit more ….

    Being an old electronics based tradesman (avionics engineer on aircraft) … I definitely know that I will trust my GPS every day of the week long before any indicating speedo. Via my GPS it always reads when I am doing exactly 100 KPH (here in Australia), (or in the USA's case MPH) my stock speedo setting reads about 102 kilometres an hour. …. Wait a minute there's another differential …

    You see by legislation, doesn't matter where we are all based world wide, every country has legislated its OK for our vehicles to be indicating to high (in other words we are actually going slower than indicated) rather than too low (which conversely mean we would be travelling above the posted speed for the area). …. That way supposedly we are never speeding. Whether that's 55 or 60 MPH in the US or 80 or 100 KPH here in Australia ….

    So where am I going here … By showing the GPS speedo indications I know straight away I am actually doing about 2% low of what is actually happening and being indicated. If that's the case, if I want to correct my speedo I have one of two options … 1) … Increase the profile of my tyre sensing wheel (rear wheel on my Spyder F3-T) or ….. 2) … (and I didn't realise this until I got right into this) … If I increase the tyres width just ever so slightly, I will actually increase the profile sizing as well, and still keep the same profile. My tyres side wall profile will actually change up very slightly ….

    So there they are! In this case, for a true speed option indication (your call) you can either increase the profile (+1 size), or go up to the next tyres width ….. For me here …. its only one or the other not both …. Going up in profile approximately doubles the change that you will get from just changing the width one size …. for example a one change size up from a 225mm tyre to a 235mm tyre, you will go up in wall profile size about 1/2" total as compared to 1" (if you were to go up one profile step instead) …

    I'm now 66 years old and always love learning something new ….

    The next phase in this …. I have (finally) worked out how I can have a 5 stud adapter made for the front wheels, enabling going to 19" or even 20" wheels and using all of the new 5 studs with no interference between the original 3 stud pattern of the Spyder ….. Then run those and still keep the same rear 15" wheel sizing …. amazing … loving the challenge …. If I wanted to be anal, I would also change the rear tyre width from the stock 225/50R15 to a 23550R15 to get that exact speedo reading correction I have just been rabbitting on so much about ...…. Cheers

    Just to prove I am not full of BS, very shortly when I do this I will post photos of the same … (PS small editing note … I've yet to delve into the realms of dyno-ing)
    did go to the 235/75/15 love it . smokey! wisconsin

    i

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •