Daft question time..(tire pressure)

[bifday2k]

Iv been going by my ybr 125 owners manual for tire pressures which states the following;

Front: 25 psi
Rear: 29 psi or 41 psi if load is greater then 90kg.

Recently i got myself a haynes manual with the intention of doing small jobs myself. I noticed that it states only rider and rider with pillion. So according to the haynes manual if its a single rider the rear should be 29 psi, no mention of wieghts and what not. It only says to use 41 psi if i have a pillion.

I am shall we say a tad bit over 90kg in weight, not massively (100 ish) but enough that i keep 2nd guessing myself when it comes to the pressure.

In my shoes what would you guys be using 25/29 or 25/41?

 

[Scythe]

Keep it to 25/29.

 

[Incinerat0r]

I would never use 41 by myself, there's no real right or wrong answer since it's ultimately what you prefer and or your uses.

In my case my manual says I should be using either 36 or 42 on the rear, I always run it at 36 or below. Keep in mind it's an R6 so the tire is bigger. When I did my track day I spoke to one of the instructors about this and they said to run your bike on the track at low 30's or high 20's, when I asked about what my manual says I was told mid 30's is good for the road.

The manual is right about one thing though, if you want to take a pillion do go and pump it up else it will feel terrible!

 

[englishpremier]

I use 42 in the rear on my bike. Seems to work well enough.

One way to test if you're running at the right pressures if to take a pressure reading cold. Then ride for a while. If the pressure rises by more than 3 psi, then your pressures were too low to begin with.

That's easier said than done though for obvious reasons. lol

p.s I could have gotten that wrong. It could be temperature that suppose to be measured. I can't remember now.

 

[bifday2k]

Pillion thing is a non issue for me atm, still riding on a cbt lol.

Cheers guys, i'll definitely test both out and see which feels better handling wise. Guess at the end of the day its more about what feels right then what a bit of paper says.

 

[Killer Carson]

Did you figure out a preference?

I was on a trackday recently and we started discussing tyre pressures and it turned out everyone of us in the garage had different pressures (on similar 750/1000cc machines) with the highest being 42 and the lowest being 22. It's a mine field and everyone tells you something different based on air temp/track temp blah blah.

I guess just go with what you feel comfortable with....

 

[Fireskull]

Highest 42 on a track day??? Geeeeees id hate the see the condition of them if he was actually pushing it....

As said its not an exact science, best bet is to start with the recommended and work from there few psi up or down, I personally have never ran recommended pressures since my 125 and my tires are always in good condition and have brilliant mileage out of them (apart from track riding... )

The 29 rear should be fine but if you feel like the rear moves around a bit try upping to 31 and see how that feels.

 

[Linkex]

I use 42 in the rear on my bike. Seems to work well enough.

One way to test if you're running at the right pressures if to take a pressure reading cold. Then ride for a while. If the pressure rises by more than 3 psi, then your pressures were too low to begin with

This sounds awfully like a 'how to find what's actually right for your bike' kind of thing. Unless someone can specifically refute this as a bad idea, I may well use this to find my bikes ideal pressure.

 

[bifday2k]

Did you figure out a preference?

I was on a trackday recently and we started discussing tyre pressures and it turned out everyone of us in the garage had different pressures (on similar 750/1000cc machines) with the highest being 42 and the lowest being 22. It's a mine field and everyone tells you something different based on air temp/track temp blah blah.

I guess just go with what you feel comfortable with....

Not really done to much testing, but i have chosen to go with 29 instead of 41, i have used both in the past, as i said in a previous post some times i would just second guess it and just go for it lol.

Just generally feels a little better, especially over bumps lol. Gonna do more testing down the line (when i remember to) and do as english and fireskull suggested if needs be.

 

[Dureth]

This sounds awfully like a 'how to find what's actually right for your bike' kind of thing. Unless someone can specifically refute this as a bad idea, I may well use this to find my bikes ideal pressure.

It's pretty bad advice, pressure change in a tyre is so dependant on environmental factors you'd never get a good reading like this. Air temperature, road surface temperature, speed at which you were riding, how long you rode for, wind speed (ally wheels are great heatsinks!), and the tyre composition/tread/wear can all affect how much pressure changes from cold to used.

The only time you want to measure hot temperatures is on a track where you are consistently pushing the tyre to a certain limit and measuring it almost immediately after coming back in. Most track day tyres have a recommended hot temperature and a suggested cold temperature which it normally around 3-5 degrees lower. I would not use the 3-5 degree difference when trying to set a road tyre as they get nowhere near as hot as when in constant high load on a track, no matter how fast your road riding is!

OP: I would suggest going for somewhere between those two suggested values as you are as heavy as a more average rider and half a pillion. So try 34-36 in the rear when cold and see if it feels more stable when riding.

 

[Dogbreath]

Not really done to much testing, but i have chosen to go with 29 instead of 41,

It's not an either/or option, you can use pressures in between these two values! I would suspect 29psi would be a little on the soft side for a heavier rider, you might want to bump it up to 32-33psi and see how it feels.

 

[bifday2k]

Cheers for that Dureth/Dogbreath was actually considering doing that, and only using the 2 values as say min/max. Seems to make more sense, so im glad someone mentioned that.

Thanks for all the input guys, its put my mind at ease for sure.

 

[acemastr]

I'm 60kg (tiny huh) and used to use 29 in the rear, should be absolutely fine with 34 or so in there.

As the others say, give it a go, but remember to get it up to temperature after you change pressure, because the pressure will always go up when hotter and could potentially cause problems with grip.

(Hence track day riders set pressures when hot, 30psi could turn into 50psi on track)

 

[CaNsA]

I always run my pressures 5psi under what is recommended in the manual, but that's cos I'm cool.

 

[MADMAN69UK]

Speed Triple manual says 42psi in the rear. I run at 36psi as recommended by the vast majority of Speed Triple riders

 

[CaNsA]

You must be cool like me then madman

 

[Killer Carson]

Highest 42 on a track day??? Geeeeees id hate the see the condition of them if he was actually pushing it....

Funnily enough, he wasn't the fastest guy. May/may not have been a coincidence