Yamaha TRX850 Enthusiasts Forum

(I've tried to search but the search ignores "tyre" for some reason...)

Anywho, I've just replaced the back tyre with a Pilot Road 2, & am now running 32 & 32psi front & rear respectivley, but when I'm throttling off around 60klm, I get headshake...

It's never happened before, but I'm thinking it's either from the mismatched tyres (Still got a Shinko 005 on the front) or the tyre pressure, before I was running 34 & 38, never had a problem. (I think 38 in the rear was a bit much because my last rear only lasted 7.5K)

Any ideas? I'll try 34 & 36 PSI tomorrow & see if that helps...

I'm running Pilot Road 2CT @ 32 front and 38 rear. Handles sweet as. I would say the problem lies with the mismatched tyres as front and rear profiles are designed to work together. Generally speaking if you mix two different tyre designs you can find trouble.
If you have changed nothing else to arrive at this problem then I think you have your answer.

Thanks Stu, I'll try some other pressures & see how it goes in the meantime. I'll replace the front as soon as I can.

a rear 2CT should run at 36psi under normal load
7.5k (assume thats KMs) is actually ok for Pilot Sport/Power 2CTs
Pilot Road 2s will give you more long life and i've not managed to over heat em yet....

I'm running 34 & 36 f/r now, it seems to have cleared up the headshake issue.

7.5K klms was with the Shinko's, single compound. If I can double that with the Pilot Road 2's I'll be happy, it's only $100 or so dearer per set.

Personally I like the pilot powers compared to the pilot road as i found i could feel the transition from one compound to the other when working them hard a little unnerving till I got used to it,but definately value for money.. The michelins with good longevity and great feel(very forgiving) are well worth the money front32psi/ rear36psi at 73kg

How many k's are you getting out of the Pilot Powers cobba?

pilot powers I got a good sticky fun 3 to 4,000km out of them but ran them right to the limit to around 7,000km and from memory a good 10,000km plus on the pilot road

tyre pressure threads always make me laugh as do recommended pressures.

unless you take your tyre pressures on hot (thermostatically controlled and calibrated tyre warmers) you are going to get a different reading. What do they mean when they say cold tyre pressure? On a December day in London or Brisbane?

FWIW, I tend to start at 36 front and 32 rear for road tyres and adjust as necessary

phuk72 wrote:tyre pressure threads always make me laugh as do recommended pressures.

unless you take your tyre pressures on hot (thermostatically controlled and calibrated tyre warmers) you are going to get a different reading. What do they mean when they say cold tyre pressure? On a December day in London or Brisbane?

FWIW, I tend to start at 36 front and 32 rear for road tyres and adjust as necessary

I agree Phuk, cold tyre pressures are for guidance/reference point only.I often stop and adjust mine while out on a run depending on the conditions, temperatures and how the bikes feeling etc.

phuk72 wrote:tyre pressure threads always make me laugh as do recommended pressures.

unless you take your tyre pressures on hot (thermostatically controlled and calibrated tyre warmers) you are going to get a different reading. What do they mean when they say cold tyre pressure? On a December day in London or Brisbane?

FWIW, I tend to start at 36 front and 32 rear for road tyres and adjust as necessary

Quite true, but peoples experience on the same bike in similar climates (like Stu99) is very helpful! Especially with the same tyres.

M.V. wrote:

phuk72 wrote:tyre pressure threads always make me laugh as do recommended pressures.

unless you take your tyre pressures on hot (thermostatically controlled and calibrated tyre warmers) you are going to get a different reading. What do they mean when they say cold tyre pressure? On a December day in London or Brisbane?

FWIW, I tend to start at 36 front and 32 rear for road tyres and adjust as necessary

Quite true, but peoples experience on the same bike in similar climates (like Stu99) is very helpful! Especially with the same tyres.

I know what you are saying but theer are so many variable - suspension set up, loads carried, speeds driven, persoanl preference etc. You think all of the Moto GP riders run the same tyres pressres?

phuk72 wrote:
I know what you are saying but theer are so many variable - suspension set up, loads carried, speeds driven, persoanl preference etc. You think all of the Moto GP riders run the same tyres pressres?

I can't say I've ever thought about it actually... from your question I presume they don't?

34 & 36 seems to be pretty good for me at the moment, I might try 38 in the rear next time I go for a big ride though, see how that goes.

Does anyone use the 4psi rule? has always worked for me. start at recommended pressure, ride until warm, check. should be 4psi higher. if higher, pressure was too low, if less than 4psi pressure was too high. Worked for me for years, and accounts for all variables.