Check your tyre pressures!

[R6_kid:Me]

Hey guys,

was just in the shop getting my sprockets changed and the nice guy also checked my tyres for me. The air that went in lifted my bike about 1-1.5cm!!!

This is just a quick shoutout to all those that are like me and often dont check theses things (waits to get burned). Also the colder weather will make the air that you put in back in summer start to lose pressure. So everyone check your tires, you never know what your missing out on (my bike is A LOT more controllable).

[Holy Roller]

I've got a slow leak so need to check the pressure each week, and always before a long ride like clockwork.

[Redstar]

The word is more pressure is better than not enough
now were have I HEARD that before?
no but square tyres are not good and to maintain the profile a bit more is better afterall all the risky stuff is on the sissy strips where tyre pressure is academic.

[Blackbird]

Tyre pressure is absolutely critical on a sports-oriented bike - that's what stops the profile deflecting and adversely affecting the handling. The heavier or faster the bike (the good ol' mass equation), the worse it gets. Surprisingly enough, I can feel a 2 psi variation from normal on the Blackbird. Look at the flats on the side of the front tyre in the photo. It has really triangled off. It's particularly noticeable towards the bottom of the photo. In this case, it was caused by the tyre deflecting (low casing strength) as opposed to low tyre pressures. It wasn't robust enough for the Blackbird and the handling was awful. Same thing happens with the wrong tyre pressures -the tyre squirms around. It's been said before on Kiwibiker, but don't trust cheap gauges and air pumps on garage forecourts. I paid around $40 for one from Motomail and it's constructed like a barometer with a Bourdon tube. A wise investment.

Geoff

[Antallica]

I'm still wondering what IS a good pressure to have (on my 150). Stock pressure says 25psi basically but I find that way too low especially for the front. I've been using 36-40psi these days but still unsure if that's a good idea. Bike's not handling horribly, just wondering.

[geoffm]

I'm still wondering what IS a good pressure to have (on my 150). Stock pressure says 25psi basically but I find that way too low especially for the front. I've been using 36-40psi these days but still unsure if that's a good idea. Bike's not handling horribly, just wondering.

Go for a pressure rise between 2-4 psi from cold to hot under normal use. I use around 2.5-3psi rise.
Geoff

[Bob]

Our friendly resident policeman will be able to shed more light on this, but I think it is worth being very careful about over-inflating your tyres.

I am not sure, but I think that could fall into the category of riding a bike that is not properly set up for the road. Which might invalidate your insurance?

Under or over inflating will affect the contact patch - too far either way has to be potentially dangerous.

Definitely check your pressures regularly though - I found I was 1 to 1.5psi down on my pressures recently. Putting that bit extra air in the tyres made a world of difference. Suddenly the bike was flicking into turns, rather than it wanting me to do a lot more work!

[Grumpy]

Shit, with the cost of tyres these days mine get checked before every ride.

[Antallica]

Go for a pressure rise between 2-4 psi from cold to hot under normal use. I use around 2.5-3psi rise.
Geoff

Rise from what? Stock pressure?

[jrandom]

I run the MT75s on my FXR at 36 rear, 32 front as per instructions from the nice man at Leading Edge.

I can definitely notice a big (adverse) difference in handling once either tyre drops more than one or two PSI. I check the pressures every week; I can 'feel' it when the tyres need topping up, for sure.

[Antallica]

Cool, I'll trust your advice.

Ant.

[FROSTY:Me]

I was gonna say I ran 30 fr 36 rear and it seemed to work well.
I prefered a slightly lower pressure on that plastic front tyre to get it working -ie semi stickyish sooner

[jrandom]

I prefered a slightly lower pressure on that plastic front tyre to get it working -ie semi stickyish sooner

Yes, the stock plastic rim protectors definitely need lower pressures than proper tyres to stop them turning into skates.

[scumdog]

Quote:"Our friendly resident policeman will be able to shed more light on this, but I think it is worth being very careful about over-inflating your tyres."

I use to run a set of 165 X 15 Pirrellis on the front of my hot-rod on 4 1/2 inch wide rimes, took 44 lbs of pressure to stop them looking flat!
On the VW type car they were meant for it would only have taken 26 lbs of pressure.
Top limit on them was 45 lbs according to printing on the side of the tyre, never had a problem though even when I spun-out on SH1 one day.

[James Deuce]

There's a great article by Tony Foale in the latest Two Wheels magazine on how the tyre footprint is affected by tyre pressure, tyre construction, and load.