Help lurker with air pressures
06-07-2005, 09:48 PM
#1
Guest
Posts: n/a
Help lurker with air pressures
Hey guys an ex lurker needs help, I run Dunlop 208ZR's, 120/70/17 and 180/55/17, I run the standard air pressure in the front, and the standard in the rear which is 42, but when the rear gets up to temp, it feels squiggly and slippery, I tried adjusting the rebound, which helped some but not alot, I think im running to high of an air pressure in the rear, what do you guys run. Oh yeah on a side note I really get the tires pretty hot, in fact my tires are pretty much melted on the side's anyone have an idea what pressures I should try. sorry about length
06-08-2005, 06:43 AM
#2
Moderator
MotoGP
Join Date: Dec 2004
Location: South Texas
Posts: 2,553
Re: Help lurker with air pressures
I don't run dunlops anymore but IIRC 42 is max. This keeps the tire cooler thus lasting longer. For better traction/feedback, run a lower psi although it sounds like your tires are "cooked" all ready.
Is the ZR a track compound? If so, you don't get many heat cycles out of these kinds of tires before they "go off" and don't feel as good.
Is the ZR a track compound? If so, you don't get many heat cycles out of these kinds of tires before they "go off" and don't feel as good.
06-08-2005, 07:30 AM
#3
Senior Member
SuperBike
Join Date: Nov 2004
Location: Richmond, Virginia
Posts: 1,315
Honda Manual calls for 36 front & 42 rear. This is quite a bit more than other bikes call for, but Dunlops website makes the same recommendation. Most sources I've seen recommend 30 - 32 PSI for trackdays, so I think it's unlikely that your tires are overheating. Heat is created by carcass flex & more heat in the tires helps them work (stick) better...up to a point.
Metzeler's website calls for 32 front & 36 rear on the Super Hawk.
I think with your agressive riding style that the standard pressures are too high for you, so you're getting too small a contact patch. Try the Metzeler recommendation & see what you think.
Also, I read somewhere this year (I think it was WEBBIKEWORLD.com) that the optimal pressure for the track could be determined based on the differential between cold & hot tire pressures. The idea was to achieve a 10% differential on the front & a 20% differential on the rear.
See attached chart that I made up. Note: I haven't had time to check this out, so it's not gospel as far as I'm concerned.
Check cold pressure, then run bike under expected operating speed & conditions. Check hot pressures. Hot pressure should vary 10% on front & 20% on the rear for optimum use.
First column is Cold Pressure, second one is Plus 10% (front) and third column is Plus 20% (rear).
Cold
Pressure Plus 10% Plus 20%
28 31 34
30 33 36
31 34 37
32 35 38
33 36 40
34 37 41
35 39 42
36 40 43
37 41 44
38 42 46
39 43 47
40 44 48
41 45 49
42 46 50
Any one else, such as racers, have some knowledge about this?
Metzeler's website calls for 32 front & 36 rear on the Super Hawk.
I think with your agressive riding style that the standard pressures are too high for you, so you're getting too small a contact patch. Try the Metzeler recommendation & see what you think.
Also, I read somewhere this year (I think it was WEBBIKEWORLD.com) that the optimal pressure for the track could be determined based on the differential between cold & hot tire pressures. The idea was to achieve a 10% differential on the front & a 20% differential on the rear.
See attached chart that I made up. Note: I haven't had time to check this out, so it's not gospel as far as I'm concerned.
Check cold pressure, then run bike under expected operating speed & conditions. Check hot pressures. Hot pressure should vary 10% on front & 20% on the rear for optimum use.
First column is Cold Pressure, second one is Plus 10% (front) and third column is Plus 20% (rear).
Cold
Pressure Plus 10% Plus 20%
28 31 34
30 33 36
31 34 37
32 35 38
33 36 40
34 37 41
35 39 42
36 40 43
37 41 44
38 42 46
39 43 47
40 44 48
41 45 49
42 46 50
Any one else, such as racers, have some knowledge about this?
06-08-2005, 10:58 AM
#4
Senior Member
Superstock
Join Date: Jul 2004
Location: Southeast PA
Posts: 409
The dunlop ZR's are a street tire. THe GP's & GP A's are the track tires.
I use the 208's on the street and run the rear at 36psi, the front at 32psi.
If you fill them to 42 they do get a slippery feeling to them, but will extend the mileage you get from them.
I use the 208's on the street and run the rear at 36psi, the front at 32psi.
If you fill them to 42 they do get a slippery feeling to them, but will extend the mileage you get from them.
06-08-2005, 11:22 AM
#5
Guest
Posts: n/a
I've been running Dunlop 208 GP-As on the street and track. I run them on the street so that I'm not always changing tires for track days and I only have one set of wheels.
I always run 28-29 psi rear and 30 front. Probably too low for the street, since I never really cook the tires street riding. But I like the way it feels on the street, even cold. On the track I roll big gumballs off the edges and it's like riding rails.
I always run 28-29 psi rear and 30 front. Probably too low for the street, since I never really cook the tires street riding. But I like the way it feels on the street, even cold. On the track I roll big gumballs off the edges and it's like riding rails.
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