Why the odd Tire/rim size's - 2012 with 14" rims front; 15" rear?

[Sampi1099]

Why would BRP put 14 inch tires on the front and 15 inch tire on the back of my 2012 RT Limited? Is this a mistake or is the way it came from the factory. Does not make any sense to me.

 

[PinkRosePetal]

14" is correct for your Spyder. It's the rolling radius that's important and 14" with the correct aspect ratio tyre gives the correct rolling radius. All good, no issue there.

 

[Sampi1099]

14" is correct for your Spyder. It's the rolling radius that's important and 14" with the correct aspect ratio tyre gives the correct rolling radius. All good, no issue there.

Why didn't they just do a 15 inch to match the rear?

 

[BLUEKNIGHT911]

Why didn't they just do a 15 inch to match the rear?

Only a BRP engineer could answer that ....... Spyders are limited in tire sizes that are currently available that will fit the wheels, fenders, fender brackets, and rear swing arm ..... to date no one has found a tire size using oem size wheels that will cause the size ratio between the front and rear to trigger a computer Fault ..... Mike :thumbup:

 

[ARtraveler]

Same way with 2 wheelers. I have two different radius size tires on my Vulcan.

 

[IdahoMtnSpyder]

Why didn't they just do a 15 inch to match the rear?

The tires are so different in size, profile, and tread that the difference in diameter has no impact of the real world use of the tire. However, the front tires were changed to 15" in 2013. Why BRP used the sizes they did, as BK says, only a BRP engineer can tell you why. And one thing we have learned, BRP doesn't ever say why they did what they did!

 

[Peter Aawen]

The increase in front rim size to 15" in 2013 was to allow space to run the greatly improved & higher spec larger sized Brembo brake calipers & discs hyea: ....and by reducing the sidewall height of the OE Spec tires up front, the rolling diameter got to remain pretty close to what it was too!

Heaps of vehicles do this, motorcycles especially, and IIRC, for many years there were very few motorcycles that had the same size front rim & tire as their rear rim & tire! Besides, with only the rear wheel driving, there's actually very little in the way of 'real' engineering or practical reasons to stick to same sized rims anyway - in fact, given their different roles (steering up front, driving in the rear - the ideal vehicle configuration & mullet too! ) and especially in the Spyder/Ryker's case, their relatively short wheel base for a non-leaning vehicle plus their pretty stable reverse trike configuration, there's arguably far more & more valid reasons to use different sized rims & tires on each end - simply look at the different front/rear tire widths & the different wear rates for easily visible evidence of that!! After all, the front & rear tires do very different jobs, and on the Spyders/Rykers there's two wheels up front & only one on the rear; only the rear wheel is driving, front wheels are steering/providing stability, yada, yada yada; so why would you even think they'd want &/or need the same sized rims or tires on each end?! :dontknow:

But as a 'just btw', I've actually ridden a Spyder that was fitted with identically sized front & rear rims & tires (on a test track & skid pan at that! ) and I can assure you that THAT particular combination seriously needs waaaayyy more mucking around with the suspension & steering geometry to get it right AND WAAAAYYYY more in the way of Nanny intervention to remain 'safe' for most ryders! :lecturef_smilie: nojoke
That's not saying it couldn't FUN (yep, definitely 'all caps' FUN! :yes: ) for any non-newbie/more competent ryders out there, but it definitely had a fair few 'serious pucker' moments & the odd 'Hardy, bring me my brown trousers' moment too; and without those previously mentioned tweaks & an upgraded/more interventionist Nanny, then would it work as the standard spec for a machine that's intended to be rideable by pretty much anyone... yeah, NO!! :shocked: In fact NO BLOODY WAY!! :yikes:

But now that you OWN your 2012 RT Ltd Sampi, and maybe you've got more than just 'a few' miles on it under its (standard sized/width) wheels, surely there's not too much to stop you from trying different sized rims &/or tires, tire sizes, sidewall profiles etc, is there?!? :dontknow: Given the number of Spyder owners we see here swapping to a/mkt rims, like the PPA rims, there's gotta be a few sets of 'take-off' OE Spec 15" rims available out there that you might be able to get fairly cheaply, or you could go a/mkt... probably cost a little more tho?! Then again, IIRC, the stud pattern that our Spyders run just happens to be the same as that on the early Smart Cars, so that opens up a whole new range of rim & rim width options, plus a few different tire size possibilities! That's where the front rims on that Spyder I mentioned above came from... and they were pretty cheap too!!

Go Onnn!! Do It - You know you want to! hyea: The world is your jellyfish :thumbup:

 

[AeroPilot]

Why would BRP put 14 inch tires on the front and 15 inch tire on the back of my 2012 RT Limited? Is this a mistake or is the way it came from the factory. Does not make any sense to me.

When we had the 11 RT it never was an issue and same way when they changed to the 15" fronts for good reasons as Peter details.

I have a bigger issue with the little donut spare tires we get with cars now, especially here in the west where you may be 100 miles from town and have a flat. Just one of the things to be aware of when you travel or need to work on your bike.

I was fortunate to find 2 Nankang 15" tires to match the fronts when we had a sidewall blowout on the 15 RT 25 miles outside of Show Low AZ two years ago.

 

[Sampi1099]

The increase in front rim size to 15" in 2013 was to allow space to run the greatly improved & higher spec larger sized Brembo brake calipers & discs hyea: ....and by reducing the sidewall height of the OE Spec tires up front, the rolling diameter got to remain pretty close to what it was too!

Heaps of vehicles do this, motorcycles especially, and IIRC, for many years there were very few motorcycles that had the same size front rim & tire as their rear rim & tire! Besides, with only the rear wheel driving, there's actually very little in the way of 'real' engineering or practical reasons to stick to same sized rims anyway - in fact, given their different roles (steering up front, driving in the rear - the ideal vehicle configuration & mullet too! ) and especially in the Spyder/Ryker's case, their relatively short wheel base for a non-leaning vehicle plus their pretty stable reverse trike configuration, there's arguably far more & more valid reasons to use different sized rims & tires on each end - simply look at the different front/rear tire widths & the different wear rates for easily visible evidence of that!! After all, the front & rear tires do very different jobs, and on the Spyders/Rykers there's two wheels up front & only one on the rear; only the rear wheel is driving, front wheels are steering/providing stability, yada, yada yada; so why would you even think they'd want &/or need the same sized rims or tires on each end?! :dontknow:

But as a 'just btw', I've actually ridden a Spyder that was fitted with identically sized front & rear rims & tires (on a test track & skid pan at that! ) and I can assure you that THAT particular combination seriously needs waaaayyy more mucking around with the suspension & steering geometry to get it right AND WAAAAYYYY more in the way of Nanny intervention to remain 'safe' for most ryders! :lecturef_smilie: nojoke
That's not saying it couldn't FUN (yep, definitely 'all caps' FUN! :yes: ) for any non-newbie/more competent ryders out there, but it definitely had a fair few 'serious pucker' moments & the odd 'Hardy, bring me my brown trousers' moment too; and without those previously mentioned tweaks & an upgraded/more interventionist Nanny, then would it work as the standard spec for a machine that's intended to be rideable by pretty much anyone... yeah, NO!! :shocked: In fact NO BLOODY WAY!! :yikes:

But now that you OWN your 2012 RT Ltd Sampi, and maybe you've got more than just 'a few' miles on it under its (standard sized/width) wheels, surely there's not too much to stop you from trying different sized rims &/or tires, tire sizes, sidewall profiles etc, is there?!? :dontknow: Given the number of Spyder owners we see here swapping to a/mkt rims, like the PPA rims, there's gotta be a few sets of 'take-off' OE Spec 15" rims available out there that you might be able to get fairly cheaply, or you could go a/mkt... probably cost a little more tho?! Then again, IIRC, the stud pattern that our Spyders run just happens to be the same as that on the early Smart Cars, so that opens up a whole new range of rim & rim width options, plus a few different tire size possibilities! That's where the front rims on that Spyder I mentioned above came from... and they were pretty cheap too!!

Go Onnn!! Do It - You know you want to! hyea: The world is your jellyfish :thumbup:

Very good advise Peter and i was just wondering why BRP would do this since its harder to find 14 inch tires. Does the speedo read from the front or rear? My spyder has over 32k miles on it so its broken in plus i have the stage II reflash and the JT's air box on it.

 

[BLUEKNIGHT911]

Very good advise Peter and i was just wondering why BRP would do this since its harder to find 14 inch tires. Does the speedo read from the front or rear? My spyder has over 32k miles on it so its broken in plus i have the stage II reflash and the JT's air box on it.

Well the " why would BRP do this ", is easy - they don't want you to use better ( ie auto ) tires ..... however the BEST spyder tire for 14in. wheels is the Vredestein Quatrac 5 tire .... they have a couple of 14 in. tires that will work fine ....... The Speedo reads from the REAR wheel ..... Mike :thumbup: