Bridgestone s21 rear tire pressure issue | GTAMotorcycle.com

Bridgestone s21 rear tire pressure issue

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awdmig

Active member
Just put new tires on, 36 psi cold front and rear. When hot the pressure are 40f and 36r, my issue is after few hours of riding the tires feel hot to touch but the rear tire pressure is not changing.

Bike feels great, suspension is adjusted (rides very well) lots of confidence leaning over.

It's 2005 r6 with a penske rear shock with an appropriate spring for me.

Should I take it down to 33psi cold?

Thanks In advance!
 
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use what is stated on your swing arm.
its always fun to play with tire psi and air / pavement temp.
 
Just a thought, but by 'checking cold' you mean before riding the bike at all right? Like 8hrs cold...
 
frekeyguy said:
use what is stated on your swing arm.
its always fun to play with tire psi and air / pavement temp.
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Most 600 (mine including) say 36/42 f/r. That's going to be much more air in the tire and it is less likely to heat up. I've had other tires and they all went up 3-5psi.
 
Tire manufacturers usually suggest their starting point, you have to play around with the pressure, for instance my pirelli tires for the street i used diff set ups but 34f/36r dead cold works best and i never check the pressure when they're hot.
Michelin tires work the best for me at 32f/34r - def you could try 33/34f instead of 36, and see from there.
 
If this is for street riding, 36 front, 42 rear. Drop the PSI by 10%-25% it's cold (10 degrees or lower).

If track riding...too many variables.

The only time my rear has stepped out on me at those pressures was on the RDT (I forgot to drop the PSI).
 
I mostly ride 31-32psi cold.
Front & rear. Depends on how stiff the carcass is.

I rode at 36psi last weekend... Was f'n scary! I don't know why people would ride at such high pressures.

Plus my suspension is setup for 32psi
 
awdmig said:
Most 600 (mine including) say 36/42 f/r. That's going to be much more air in the tire and it is less likely to heat up. I've had other tires and they all went up 3-5psi.
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isn't 42 rear for fully loaded/max GVW?

Either way, for street riding I check cold pressure and have never checked it hot.
 
sempre1 said:
I'm assuming street riding right?
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Yes, spirited and lots of back road twisty stuff
油井緋色;2418515 said:
If this is for street riding, 36 front, 42 rear. Drop the PSI by 10%-25% it's cold (10 degrees or lower).

If track riding...too many variables.

The only time my rear has stepped out on me at those pressures was on the RDT (I forgot to drop the PSI).
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Well I'm having trouble with the rear pressure holding at 36psi hot and cold so I don't think it would be good to go for 42 in the rear, maybe you can help me understand the point better...I would appreciate it.

sempre1 said:
Tire manufacturers usually suggest their starting point, you have to play around with the pressure, for instance my pirelli tires for the street i used diff set ups but 34f/36r dead cold works best and i never check the pressure when they're hot.
Michelin tires work the best for me at 32f/34r - def you could try 33/34f instead of 36, and see from there.
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My front is doing great, feels good etc and goes from 36 cold to 40 hot so maybe just the rear?
 
Riceburner said:
isn't 42 rear for fully loaded/max GVW?

Either way, for street riding I check cold pressure and have never checked it hot.
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I have to look again but I believe my swing arm says 180 lbs 42psi. It's pretty much an industry standard, checked my buddies zx6r 2011 and it says 36f/42r for 180lbs.

I'm 165 with gear 180ish
 
I would assume that since the front tire is smaller than the rear that as the temp goes up the rear pressure does not go up because the larger tire can expand a bit more than the smaller front so the rear will not get as high a pressure.

I always work with the 10% rule meaning if your hot pressure is 10% higher than the cold pressure then it is within the correct range.

Eg. Front tire cold reads 32psi (10% of 32 is 3.2 so 32 cold plus 3.2 so hot pressure would be 35.2psi) so if it reads hot around 35-36 then you are almost perfect.

Same for rear if you have 42 cold and add 10% (4.2) your hot reading is 46ish then you are bang on.

On the same hand if you had 42 cold and hot it was 48 then it has increased more than 10% so lower your cold down next time and recheck.

Once you get it right your hot pressure should read 10% higher than the cold pressure. And of course it will change based on how hot the road is too so changes spring and fall compared to summer.
 
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Try on a nice hot day 32f/30r for max grip on a twisty roads and see how she feels, the next day for commuting add just more pressure and look at the wear.
 
So the tire pressure doesn't fluctuate when riding and you don't have any grip issues? I don't see any problems. 42psi will help you get the back tire spinning and sliding if that's what you're after.

I never checked hot pressures when riding on the street. If the tire is working the way you want it to, you've found the pressure you should start at before the ride and the smiles kick in. Unless your trying to treat the GTA like the IOM then you might want to get more serious about this and start with warmers in the garage to make sure you get a consistent reading :)
 
dricked said:
So the tire pressure doesn't fluctuate when riding and you don't have any grip issues? I don't see any problems. 42psi will help you get the back tire spinning and sliding if that's what you're after.

I never checked hot pressures when riding on the street. If the tire is working the way you want it to, you've found the pressure you should start at before the ride and the smiles kick in. Unless your trying to treat the GTA like the IOM then you might want to get more serious about this and start with warmers in the garage to make sure you get a consistent reading :)
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I'm not trying to spin up the rear tire so I'm not sure where you got that idea from especially since you have atleast some idea on why I made the thread, dont have anything constructive to say then maybe you should stick to the OT forum

Its a new tire in the market and its not fluctuating as you said, just trying to see what others, more knowledgeable riders think of that and learn from their experience. If I was born with all the knowledge of the world like yourself I wouldn't be here getting ridiculed by you, some guy I dont know for not assuming its all good
 
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Dude relax..... you were just getting advice from a pro level rider.....
 
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awdmig said:
I'm not trying to spin up the rear tire so I'm not sure where you got that idea from especially since you have atleast some idea on why I made the thread, dont have anything constructive to say then maybe you should stick to the OT forum

Its a new tire in the market and its not fluctuating as you said, just trying to see what others, more knowledgeable riders think of that and learn from their experience. If I was born with all the knowledge of the world like yourself I wouldn't be here getting ridiculed by you, some guy I dont know for not assuming its all good
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There was constructive advice in there, maybe try reading it again without getting your lady bits full of sand. Someone else recommended a high pressure and I told you what would happen if you followed that advice. The end was a joke. From now on I'll refrain from giving you advice as it's clearly not appreciated.
 
lol honestly how did you get offended by what dricked said? there was even a smiley at the end for god sakes.
 
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