just curious...

[Laila's Dad]

Hello all,


I am honored to share another day that ends in Y with you...I see that after 2012 BRP increased the size of the stock front tires to 15 inches. Now of course that isn't a size 17 inch or larger but what is the deal with larger aftermarket tires and why dealerships won't touch them? My spyder is stock, but from what I have been told once you add the larger rims/tires then you have to deal with a personal mechanic or do it yourself as for repairs concerning them. The Spyder doesn't lean so in my non-mechanical mind I am thinking that it shouldn't matter the tire size as long as there is good tread, right? Now of course I know some guys who got in trouble with the "Nanny" when they added big tires, but for the guys who don't have issues with the VSS/ABS stuff they still have to go away from the dealership... Not looking for anyones personal opinion about what looks good or not, but for those of you that know why or have a mechanical opinion of why the larger tires and speakers are pretty much taboo at dealerships.

[Dan McNally]

I suspect that BRP dealerships stay away for reasons of liability . . . lawyers are behind most "better not do that" decisions by businesses . . .

[ThreeWheels]

The outside diameter of the front tires are all the same. The nanny compares the RPM of the tires to calculate if one or more tires are slipping.
Going to a 15 inch rim has two advantages.
First, the shorter sidewall doesn't flex as much, giving a performance enhancement in that the tires are stiffer and deform less during turning.
Second, the larger rim provides more room for bigger brakes, another performance enhancement during braking.
The downside is, there are very few tires available I n what has become an unusual tire size.
Because the nanny, a safety system is linked to tire size, BRP is reluctant to give permission to owners to use any tire that has not been specifically tested with the Spyder for reasons of liability.