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)
rear tire i did go to 235 tire love it
Quote:
Originally Posted by
fatenhappy
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
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