Front tyre pressure - Wrist Twisters
 
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post #1 of 14 Old 02-01-2014, 05:10 PM Thread Starter
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Front tyre pressure

So I discovered last week that my front tyre [Pirelli Diablo] has 3 modes:

- low pressure, feels heavy on the steering, mushy; this mode is pretty obvious, and happens because the front seems to leak air molecules out in to the world more quickly than the rear - it's a reminder to get eh pressures back up;
- the sweet spot - lots of feedback, very confidence-inspiring, grippy;
- over-inflated - hard, feels like a piece of timber, doesn't slip but feels like it could, hard to get it to load up, feels like it might skate out at any stage.

Fortunately, I found this out before I did about 1200km in the last 3 days.

I was prepping my bike for the impending trip earlier in the week, and had been squirting around town on it, really liking how the front was feeling. But thinking "long trip, open road", when I went to check the tyre pressures, I put a few more pounds in both ends and headed out on the [city] streets again, and immediately noticed that I had lost all the good feel from the front. I think I pumped the front to 33 lbs [gas station reading] so dropped a couple pounds out at the next gas station, and got the good feel back.

I bought a digital pressure gauge not long after, and will monitor the pressures much more closely.On the open road over the past few days in hot weather, the front was reading 31.5, and still had some bite and feel. After a night in the garage, it read 28lbs this morning.

The rear was showing 36lbs in the heat yesterday, 33 this morning.

So, this was all very interesting learning - in the past, I have probably been running the front too hard on the open road, and losing that nice grippy feel. This time, I enjoyed the whole trip as much as any ride I've ever done.

I'll use the pressure gauge in future to get an idea of the upper and lower limits of the sweet spot, but it was certainly an education about how too much pressure can be a bad thing.
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post #2 of 14 Old 02-01-2014, 05:26 PM
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thats typically what i run is about 28 / 28 to 30/30 front / rear

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post #3 of 14 Old 02-01-2014, 06:04 PM Thread Starter
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Yeah, I'm going to stay on the low side in the future, for sure.

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post #4 of 14 Old 02-06-2014, 01:42 PM
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Thanks guys i did notice the front tire feel like it slides a bit. So after reading this i checked my tires i was runnin 34 front and 30 rear. I made them both 29psi and its like night and day

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post #5 of 14 Old 02-06-2014, 02:28 PM
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Hmm, I run 36 front and 42 rear.

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post #6 of 14 Old 02-06-2014, 03:05 PM
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Quote:
Originally Posted by Cloroxbleach4 View Post
Hmm, I run 36 front and 42 rear.
As do a lot of ignorant riders out there.

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post #7 of 14 Old 02-06-2014, 03:29 PM
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As do a lot of ignorant riders out there.
off by about 4-5-6 psi

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post #8 of 14 Old 02-06-2014, 04:40 PM
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post #9 of 14 Old 02-06-2014, 05:13 PM
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Quote:
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30/30 it is then!
why 30/30?

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post #10 of 14 Old 02-06-2014, 05:42 PM
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Quote:
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why 30/30?
That's what I took away from this thread.. am I wrong? What do people usually run?

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post #11 of 14 Old 02-06-2014, 10:42 PM Thread Starter
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Quote:
Originally Posted by Cloroxbleach4 View Post
That's what I took away from this thread.. am I wrong? What do people usually run?
You could try leaving the rear a little higher, like a [cold] combination of 28 / 31 or so.

See how it feels - I don't know that my experience will replicate for all tyres and all conditions - we've got summer, for starters - but the front will let you know pretty quickly.

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post #12 of 14 Old 02-07-2014, 03:34 AM
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Quote:
Originally Posted by Cloroxbleach4 View Post
That's what I took away from this thread.. am I wrong? What do people usually run?
It all depends how you want your bike to handle, personal preference. If I understand this correctly, LDH is referring to "ignorance" as those numbers are user manual numbers - maximum full load on the bike (passenger and some lagage) So if you have 400lbs + on your bike all the time.....
Depending on the weather/road conditions, I've used range 30to34. On the supermoto I've run as little as 20,22 and usually stay around 25. But again, those tires are made for heavier bikes than my little Dzer.

Try different pressures and see what feels best for you. I've met people that run high 30s-low40s which is crazy IMO but... whatever floats their boat, I guess

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post #13 of 14 Old 02-07-2014, 03:49 AM
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Yeah, I had to air mine up last night, they were a couple pounds low. She always feels too slugish to me when the pressures drop. I usually run 30-32 front and 36-38 rear. She just seems to handle better to me with this set up, but then again I'm on 100% stock suspension and PR3's.

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post #14 of 14 Old 02-07-2014, 08:10 AM
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29/30-31 for me. I think I was actually running almost 33/34 cold at the last track day, and I could tell, I didn't have the traction I wanted.

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