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I have a true answer about the cold track pressures.

Ssketchy RC

Ssketchy RC

New member
Joined
Feb 14, 2002
Location
Dallas Texas Bitches
Moto(s)
CRF 250X, 1965 Honda S65
So I got all sorts of confused by the conglomerate of answers to the post so I called Michelin, Freddie Spencers School, and AFMotorsports. I haven't heard back from AFM yet but it appears that the H2's take a really hard beating at T-Hill. Especially on the bigger hp or torque bikes. They reccommended that I run the H2 front and M2 rear. And as far as the pressure goes to run at 28/29 is great for colder days but there isn't going to be a need for that much of a drop if you are only talking about low 60 degree temps. 29/30 should be fine or even 30/31. These are just starting points and shouldn't be used as definates but that seems to be a general concesus. Thanks for all the input guys I just wanted to clarify what I had found. I will let you know if AFM says differently.
 
This doesn't make sense. If the H2 takes such a beating, why would they recommend the M2, which is the Medium Compound compare the the H2 which is the Hard compound. A Medium compound will provide better grip but won't last as long in comparison to the Hard compound.

Also, it doesn't make sense to run H2 Front (Hard), and M2 Rear (Medium). I would think that a S2 (Soft) front with a M2 rear would be the best bet at T-Hill. I like to have softer fronts than rear.
 
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H - Believe it or not doesn't stand for Hard

S2 - Soft
H2 - Semi-Soft (Street compound)
M2 - Medium

That is per the Michelin rep, which at the time of the racer into was Morgan Broadhead, distributed through Freddie Spencer.

If anyone needs further clarification, call Alex Florea at 650-400-3461.
 
kneedrag said:
H - Believe it or not doesn't stand for Hard

S2 - Soft
H2 - Semi-Soft (Street compound)
M2 - Medium

That is per the Michelin rep, which at the time of the racer into was Morgan Broadhead, distributed through Freddie Spencer.

If anyone needs further clarification, call Alex Florea at 650-400-3461.
Click to expand...

TY Shawn. I guess I was full of shit. I was told by some racers who run them, about the diff. tires compounds. I guess they didn't listen well to their Michelin Rep. :)
 
Ssketchy RC said:
yeah the 28/29 stands for frony and rear. Didn;t mean to cause such a controversy. lol
Click to expand...

You're serious? Hrm. Everything I've heard for tire pressures always puts the rear lower than the front... wonder why that is.
 
morthrane said:
You're serious? Hrm. Everything I've heard for tire pressures always puts the rear lower than the front... wonder why that is.
Click to expand...
less contact patch on front = greater psi against the outside of the tire casing = more psi inside the tire to maintain carcass shape and compliance of the tread. The larger volume in a rear tire means more rubber is on the ground, less psi as an outside force. Here are some rough figures for example:

Front Tire: 100 lbs on a 1" x 1" patch on the ground = 100 psi
Rear Tire: 100 lbs on a 2" x 2" patch on the ground = 25 psi

Easier example. Mountain Bike tires typically run 35-40 psi. Road/10-speed tires typically run 9-120 psi.
 
Ssketchy RC said:
You are right about that. I meant it the other way. I am used to car tires so I fliped them. My bad.
Click to expand...
Even on car tires, you want 1-2 psi more in the front tires, again for the same reason. Most cars are 51/49 to 53/47 front/rear weight distribution. If you have the same pressure in all 4 tires, the fronts will compress more, changing the contact patch, making it slightly larger. With 1-2 psi more, it makes up for the extra weight distribution and gives you close to 4, equal contact patches. This also will keep tire wear even as you get the same amount of rubber on the road and same casing deflection. ;)
I only thought about this because the guy at my normal tire place made the comment of, "run less in the front so the car doesn't have as harsh a ride, due to the heaviness of the engine." :confused:loser:laughing
 
Its true the M2's are a different compound than the H2's therefore giving it the nod for T-hill along with an H2 front is the ticket.
And yes the rear should be 1-2psi lower than the front because of the forces being applied under acceleration/power.

BD
 
Hey Chuci... Hate to be ther bearer of bad news but any higher performance cars run lower pressure in the front then the rear. It has been that way for quite some time. For instance..... Mercedes 2001 CLK 320 205/55r16 32/33. 1995 E320 195/60r15 27/30. All BMW's seem to run higher rear pressure even with the same size tire all the way around. Now on the staggered fitments dealing with higher performance vehicles (which should be used to compare to a bike seeing as how we have different sizes) run higher in the rear on the wider tires. I do know a little bit about this stuff being that I run a tire shop. And my point of reference is the Michelin fitment guide from 2001. On some cars like smaller touring cars the do run either the same or sometimes lower in the rear but that is for touring NOT for any type of high performance driving. Just wanted to clear that up. :teeth
 
The metzler Rep told me to run 31 fr 29 rr in the Rennsports
 
TrackHo thats very consistant info from what I've gathered as well when using Renns or other brands also. I'll most likely be using Renns once winter is over as I like them even though their a bit costlier.

BD
 
Here is the E mail I received from AFMotorsports. Hope this clear up some stuff.


Jeremy,

We just got back from Thunderhill from the AFM races
and the track is VERY abbrasive this time of year. It
almost seems like when it's really cold or really hot,
the track doesn't tear up tires that bad, but when the
temps are around 80 degrees, T-hill destroys tires.
On Friday, I actually got a call from my good friend
Terry Newby (Dunlop race tire dealer for west coast)
and he told me both his and Pirelli's tires were
getting chewed up, so I should bring the hardest tires
I can get my hands on. A couple of racers were using
H2s, but the rear tire started tearing up pretty good.
They were also going at a slightly faster pace than
what you wrote, so that may have been a factor.

The M2 rear is the "bulletproof" tire at T-hill and I
highly recommend it, but since we will be there for
PacTT providing their tire service, I would suggest
using the H2s and see if they'll last for the day. If
they don't, we're there to help you mount up a new
tire, but I'm a racer "on a budget" myself and I know
you would probably rather not spend the extra money if
you don't have to... ;-) The M2 looks exactly like
the H2, but it is a harder compound - I know, I know,
you would think M stands for medium and H for hard,
but it's just not like that. Don't ask me why
Michelin gave them those names because I've had to
explain that hundreds of times this year!

The air pressure we normally start with is 30 psi on
the front and 28 psi on the rear. Oh yeah, almost
forgot: next time you buy Michelins, at the very least
upgrade to the S2 front - it is a better race/track
tire than the H2 front!

Hope that helps,

Alex Florea
www.afmotorsports.com
650-400-3461
 
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