Typical Air Pressures for Tires??

[gs750guy]

On my 78 GS750, I notice that my owners manual says to put 28lbs in the rear and 25lbs in the front........however the markings on my D404 Dunlops say to put 38 in the rear and 34 in the front.
Which pressures should I use.......the manual or the tire markings??????

GS750guy

[cowboyup3371]

Start based on the tire markings and then judge using the 10% rule as mentioned above in this thread.

[Steve]

On my 78 GS750, I notice that my owners manual says to put 28lbs in the rear and 25lbs in the front........however the markings on my D404 Dunlops say to put 38 in the rear and 34 in the front.
Which pressures should I use.......the manual or the tire markings??????

GS750guy

The tire manufacturer has no idea how heavy the bike is that is going to be wearing those tires. The pressures that are listed on the sidewall are the MAXIMUM (cold) pressures that should be used. Those are the pressures required to handle the maximum rated weight at the speed rating for the tire. You will probably not need those pressures on a daily basis.

Your best bet is to use the 10% rule that is mentioned above.

.

[Suzuki_Don]

My situation is I have had new tires fitted and they are run in now. A Metzler Lasertec 3.25x19 on the front and a BT45R 110/90-18 on the rear.

I had set the front tire pressure at 27 psi and the rear at 30 psi.

After a run to fully warm the tires up the pressures were front 30 psi and rear 34 psi.

So I changed the pressures to 28 front and 32 rear and after another warmup run (on a different day) they came back as 29 front and 36 rear.

So the front tire needs to go back to 27 psi to be somewhere near the 10% increase that is recommended. But I don't know anyone that is running a front tire with that low a pressure.

The rear tire came back as 36 psi and the 10% of the cold 32 psi should add up to 35.2 psi; so the rear tire is about right.

What do you guys think about the 27 psi in the front tire, does it seem too low even though it complies with the 10% rule. BTW it is on a GS550 which weighs in just under 200kg.

Opinions thanks?

[Billy Ricks]

10%, ten percent, 10 percent, how many other ways can it be stressed? The bike and tire manufacturers have no way of knowing what tire and bike combinations will be used. 10% gets the most traction and performance out of your tires.

[GS750]

My situation is I have had new tires fitted and they are run in now. A Metzler Lasertec 3.25x19 on the front and a BT45R 110/90-18 on the rear.

I had set the front tire pressure at 27 psi and the rear at 30 psi.

After a run to fully warm the tires up the pressures were front 30 psi and rear 34 psi.

So I changed the pressures to 28 front and 32 rear and after another warmup run (on a different day) they came back as 29 front and 36 rear.

So the front tire needs to go back to 27 psi to be somewhere near the 10% increase that is recommended. But I don't know anyone that is running a front tire with that low a pressure.

The rear tire came back as 36 psi and the 10% of the cold 32 psi should add up to 35.2 psi; so the rear tire is about right.

What do you guys think about the 27 psi in the front tire, does it seem too low even though it complies with the 10% rule. BTW it is on a GS550 which weighs in just under 200kg.

Opinions thanks?

27psi is fine in your front tyre!

I know that it aint a bike but my HQ tonner ran 295/50/15's and only 18psi fully loaded around town and 20psi on highway and I got almost triple the k's that I did when running 30psi!

More of a concern to me from my own personal experiences is that I would NOT be running mixed tyres, (Your metzler front with the bridgy rear).

I had nothing but troubles when i did that on my GS750.

The BT45's were no good on my bike at all. They wore too fast even @ 10% and were just really crappy grip compared to the lazertec's

[Suzuki_Don]

27psi is fine in your front tyre!

I know that it aint a bike but my HQ tonner ran 295/50/15's and only 18psi fully loaded around town and 20psi on highway and I got almost triple the k's that I did when running 30psi!

More of a concern to me from my own personal experiences is that I would NOT be running mixed tyres, (Your metzler front with the bridgy rear).

I had nothing but troubles when i did that on my GS750.

The BT45's were no good on my bike at all. They wore too fast even @ 10% and were just really crappy grip compared to the lazertec's

Andy, I did mix the tires on the advice of the dealer (owned the shop for 30+ years) and I popped in and saw him the other day and he said the pressures I was using were way too low. Said I should be going with 34 front and 36 rear. I wasn't quite game to use the 34 in the front and went with 32F and 36R. Well let me say that it has transformed the bike. It is like it is on rails now, it goes exactly where I point it, it doesn't have the vague feeling it had before. It rockets through the corners now and doesn't change line at all. I couldn't be happier, even if I am riding on MIXED tires.

[GS750]

Andy, I did mix the tires on the advice of the dealer (owned the shop for 30+ years) and I popped in and saw him the other day and he said the pressures I was using were way too low. Said I should be going with 34 front and 36 rear. I wasn't quite game to use the 34 in the front and went with 32F and 36R. Well let me say that it has transformed the bike. It is like it is on rails now, it goes exactly where I point it, it doesn't have the vague feeling it had before. It rockets through the corners now and doesn't change line at all. I couldn't be happier, even if I am riding on MIXED tires.

Win win then Don

Im in central (coastal) Queensland and on my '77 GS750 with lasertec's I have found that 28-30psi front and 30-34psi rear was great
On top of the 235kg of bike with fuel etc, I then sit myself @ around 100kg

My local dealer advised me that I should run 36 front and 40 rear :O WTF....
Just for laughs when I got my last set fitted I tried his suggestion for 2 weeks and yes, it felt faster and quicker into the corners, but I had so much more vibration that I did not like that at all, plus it meant that it had less contact patch so I found when I was going off the edge of the highway onto the dirt shoulder I had to use less brake or the wheel/s would lock up :O

I usually get 11000km from my rear every time but I am not light on the throttle either

[Suzuki_Don]

That all sounds good Andy and with your comments in mind I think the 32F and 36R is a good compromise for me. Good quick steering, bike feels stable, no movement in corners and the ride is a little harsher but I can handle that considering the other benefits.

Thanks for the valuable comments.