tire pressure question

[swoods]

hello,

I'm new to motorcycles in general, but have been fixing up a '79 GS550E for a couple months. I got the bike really cheap from a guy who had moved and his parents wanted it out of their garage. With limited mechanic experience, I managed to get it running (cleaning all the carbs). Then had to figure out why it was still leaking fuel even though the floats weren't sticking (this was the petcock). Fixed all that, plus some issues with the blinkers. Running great now though.. I think

My question is this: It needed new tires. They were pretty cracked and I could not even figure out how to date them according to the code. There is no 3 or 4 digit number. Only 2 and I'm not sure if that's supposed to be a dating system.

So I took it to the shop to have the tires replaced, because I was running out of time (maybe a little patience) and didn't want to learn how to balance tires also. I drove the bike home today and decided to check the pressure to see what they set it at. The back was at about 32psi. The front..... 91?! Is this normal? I know that they did have to put a tube in the front tire. Would that require higher pressure? I dropped it to 33psi right now...

Was that high pressure right? Or should I call the shop and say something. The tires are Dunlop 404's. That's the best I can remember for now.

Thanks

[Nessism]

91 psi is crazy high. They must have used a lot of pressure to get the bead to seat. I'd call the shop and complain - tell them you want a new tire. The cords in the tire can get damaged with that much pressure - you should never go over 50 psi or so.

[Billy Ricks]

If it has 91 lbs of pressure in it there is a very good chance the integrity of that tire is now compromised as Ed has already pointed out. The correct pressure for any bike is about 10% higher hot vs cold. That means check your tire pressure cold then go for a brisk ride and recheck pressures. You should see about a 10% rise in pressure. If it is less you are running too much air and the tire is not heating up properly. Higher than 10% means you're not running enough pressure and the tire is heating up too much.

[Steve]

Start with about 33 or so in each tire, but record what you put in there, so you don't forget it. Go for a ride of at least 25 miles to warm up the tires, check the pressure again. You are looking for a 10% increase in pressure. If you see about 36 psi on the warm tires, you have the right pressure. If you get more than 10%, the tires were flexing too much and got hot enough to warm the air, raising pressure. Bump up the cold pressure a couple of pounds and try again on another day. Conversely, if you did not get a 10% raise in pressure, your cold pressures were too high, not allowing the tire to flex enough, so drop the cold pressure a couple of pounds and try again.

By the way, if you regularly ride with a passenger, you need more air to handle the extra weight, so you have to do your pressure testing again.

.

[swoods]

I'll call and check with the shop on Tuesday (they won't be open memorial day). Should I not ride it any extra except to the shop?

Billy- I did notice that the back tire was hotter than the front when I got home. Probably why. Good advice on the 10% thing, thanks.

[swoods]

By the way, if you regularly ride with a passenger, you need more air to handle the extra weight, so you have to do your pressure testing again.

.

No passenger yet since I don't have my license, but i should be getting that soon. I did know that it needed to be higher then.

[alke46]

91 psi is crazy high. They must have used a lot of pressure to get the bead to seat. I'd call the shop and complain - tell them you want a new tire. The cords in the tire can get damaged with that much pressure - you should never go over 50 psi or so.

Good luck getting any satisfaction from the shop. They are not going to believe you when you tell them it had 91 psi., especially since you have already lowered it to 33.

[Steve]

They must have used a lot of pressure to get the bead to seat. ...

Usually not much of a bead to seat with a tube-type rim.
They don't have that extra ridge on the rim that the tire needs to pop over, so they don't usually need a whole lot of pressure.

.

[Nessism]

I put Dunlop 404's on my old 450 and they were a real pain to get seated - took a lot of pressure, but NOT 91 psi. Must be a characteristic of that particular model tire.

[swoods]

I figured 91 was waayyy too high. It was high enough that I heard pinging in the tire on my gravel driveway. You know like when you have a high pressure bicycle tire and ride it on gravel?

Hopefully the shop gets me a new tire. I mean, it's not like I really have reason to lie and get a new tire when I just got one. Plus they've had the chance to get to know me pretty well.

No one answered this yet, but should I avoid riding it? I kind of wanted to go on a good ride tomorrow with some friends, but maybe I shouldn't?

[Billy Ricks]

I figured 91 was waayyy too high. It was high enough that I heard pinging in the tire on my gravel driveway. You know like when you have a high pressure bicycle tire and ride it on gravel?

Hopefully the shop gets me a new tire. I mean, it's not like I really have reason to lie and get a new tire when I just got one. Plus they've had the chance to get to know me pretty well.

No one answered this yet, but should I avoid riding it? I kind of wanted to go on a good ride tomorrow with some friends, but maybe I shouldn't?

I don't think anyone wants the liablility involved with saying it's okay. It probably is fine now that you have adjusted the pressure where it should be but who knows for certain?

Here's something you might want to print up and take with you to the shop that mounted the tire.

http://www.agcoauto.com/content/news/p2_articleid/97

[swoods]

I don't think anyone wants the liablility involved with saying it's okay. It probably is fine now that you have adjusted the pressure where it should be but who knows for certain?

That's true about the liability thing. I should have said "would you ride it like that?" It rained today anyway, and hopefully I can take it to get it fixed now. I'll post an update when I see how the shop responds.