I know, it's been nearly beat to death, Tires

[ButterSmooth]

MNF3, the tire rating of 1477# @ 44psi = 33.57#/psi. My load with a 150# single rider is 750# front, 500# rear. Your load is 220# higher (not including gear) than mine. That puts ~110# more on the front and ~110# more on the rear. With a rear load of 610# the starting pressure for the rear can be as low as 18psi. (610/33.57), so 18psi should be an ok starting point. I like that you are thinking about the load. If you find an open scale when your out riding all loaded up, pull in and get your actual axle weights. Pay attention to 'squishy' side-to-side feelings in the corners -- if it's not 'solid' feeling you may need more pressure. Check the pressure right after a ride -- it shouldn't go up more than 4psi.

 

[BLUEKNIGHT911]

MNF3, the tire rating of 1477# @ 44psi = 33.57#/psi. My load with a 150# single rider is 750# front, 500# rear. Your load is 220# higher (not including gear) than mine. That puts ~110# more on the front and ~110# more on the rear. With a rear load of 610# the starting pressure for the rear can be as low as 18psi. (610/33.57), so 18psi should be an ok starting point. I like that you are thinking about the load. If you find an open scale when your out riding all loaded up, pull in and get your actual axle weights. Pay attention to 'squishy' side -to-side feelings in the corners -- if it's not 'solid' feeling you may need more pressure. Check the pressure right after a ride -- it shouldn't go up more than 4psi.

:agree: ...... except for the side to side feeling " Squishy " ..... Tires today are almost entirely Radials, and they often feel Squishy at this LOW a PSI. .... When on a Twistee road " G " forces come into play. As the wheel / rim moves sideways you want the TREAD to remain as flat as possible. And this will happen ( on Spyders ) with the recommended PSI's.... Mike :thumbup:

 

[MNF3]

Thanks! I’ll give 18 a try.

 

[TRBorslien]

Hey Mike,

Looking to replace my Kumho Ecsta rear very soon. I know the fronts on earlier Spyders were a different size so I want to make sure about the rear. Will the Riken Raptor HR 215/60-15 fit on my 2012 RT?
Apologies if you already answered this, but I didn't see it in any of the Riken posts. TIA!

P.S. Love, love, love the Vredestein Quatrac 5's on the front!

 

[BajaRon]

Hey Mike,

Looking to replace my Kumho Ecsta rear very soon. I know the fronts on earlier Spyders were a different size so I want to make sure about the rear. Will the Riken Raptor HR 215/60-15 fit on my 2012 RT?
Apologies if you already answered this, but I didn't see it in any of the Riken posts. TIA!

P.S. Love, love, love the Vredestein Quatrac 5's on the front!

Yes, the 215/60/15 tire size will fit any Can-Am Spyder rear. It is taller and narrower than stock. The taller is actually good because it brings your speedometer closer to reality.

 

[BLUEKNIGHT911]

Hey Mike,

Looking to replace my Kumho Ecsta rear very soon. I know the fronts on earlier Spyders were a different size so I want to make sure about the rear. Will the Riken Raptor HR 215/60-15 fit on my 2012 RT?
Apologies if you already answered this, but I didn't see it in any of the Riken posts. TIA!

P.S. Love, love, love the Vredestein Quatrac 5's on the front!

:thumbup: ...... read what Ron just posted ( #25 ) :agree: ..... and glad you Looooooooooooooooooove the Quatrac's :clap:....Mike :thumbup: Folks here who bought and mounted that Riken are also very happy with it ....especially at that price ....

 

[TRBorslien]

Thanks Ron and Mike!

I will order a Riken Raptor and I always appreciate the advice you both provide.

 

[Steve W.]

MNF3, the tire rating of 1477# @ 44psi = 33.57#/psi. ...

I like your train of thought, but please be aware that it's not quite a linear relationship. That is, there is some strength in the empty tire, and additional air will add to it.

That said, your formula is close, and is also the foundation for figuring recommended pressures for tires that are not rated at 44 psi.

Also, while this formula may not give you the exact pressure to run, it will at least give you an idea where to start. :thumbup:

.

 

[ButterSmooth]

I like your train of thought, but please be aware that it's not quite a linear relationship. That is, there is some strength in the empty tire, and additional air will add to it.

That said, your formula is close, and is also the foundation for figuring recommended pressures for tires that are not rated at 44 psi.

Also, while this formula may not give you the exact pressure to run, it will at least give you an idea where to start. :thumbup:

.

Absolutely; The intercept is not zero, so it's just a way to get a reasonable starting pressure. How it handles, wears and rides are the biggest factors -- and checking the pressure rise as the tire warms is another good indicator. I think it's a move from "...in my experience..." to a SWAG that at least uses the specific tire's specifications and load.

 

[MNF3]

I’ll see what kind of pressure rise I get with 18psi. I didn’t get a chance to check it at 20psi when we were at SITO.

 

[BLUEKNIGHT911]

I’ll see what kind of pressure rise I get with 18psi. I didn’t get a chance to check it at 20psi when we were at SITO.

Just to clarify, the PSI's that both Peter and I recommend are based on the Normal rise in pressure caused by heat from Riding your Spyder...... Peter & I rely on TIRE SCIENCE ...... not " feeling's " ..... good luck .... Mike :thumbup: