Tire Pressure question

[GS750GUY]

GS750GUY here again,
My new Dunlop tires indicate a cold pressure inflation of 41 Lbs on the tire stamp itself for both front an back. However, my manual recommends 38 in the rear and 34 in the front. Which should I go by....the tire or the manual?
GS750Guy

 

[Nessism]

41 psi is the max pressure, not the normal running pressure.

Tire pressure varies depending on load and intended usage. For loaded touring, crank up the rear tire pressure to the high end of the specification range.

Below is the tire pressure recommendation for the 850 model. You're 750 should be similar.

.

 

[chuckycheese]

Pressure

Pressure

I'd be curious to know what the maximum suggested pressure was for tires in 1980. I'll bet it was considerably lower than for the tires these days. Thus, I think running higher pressure nowadays is probably fine. I run about 35 and 38 and can notice a big difference (not a good one) if I go as low as the suggestion on the bike sticker.

 

[Billy Ricks]

Not it's not okay to run maximum pressure when it's not needed. I linked a Dunlop paper on this at one. Run the recommended factory pressures.

 

[twr1776]

I have seen a number of similar posts before on this topic and have wondered if you should base your pressure on the new tires listed pressure recommendations instead of the OEM tire pressures listed in the owners manual. Since the tires are not the OEM tire that came with the bike I would think you should go with the new tires recommendations. Anyone know for sure? On the same topic is there a typical pressure percentage or poundage under the maximum pressure listed that you run your tires or do you adjust as you go?

 

[twistedwankel]

GS750GUY here again,
My new Dunlop tires indicate a cold pressure inflation of 41 Lbs on the tire stamp itself for both front an back. However, my manual recommends 38 in the rear and 34 in the front. Which should I go by....the tire or the manual?
GS750Guy

The psi differential is important for handling. The actual psi is adjusted according to your riding style. You would want more pressure if you are loading (racing) the sidewalls in hard turns front and rear. If carrying more weight in the back (passenger) you would want about 6psi more than the front to support the weight. You will gain about 4psi when the tire is up to temperature from hwy. driving about 10 minutes.

I use the factory recommended cold 25f and 28r for my 81 750E and soft #2 settings on the rear shocks too for all around comfort on my new Dunlop 404's. I only lay it over about 45degrees max about 1/2" from the tread limit but enough to wear off the rear yellow marker line.

(When I autocross my rwd 84 car I run 7 psi more than recommended cold to get rid of sidewall flex and heat build/chunking on those all season full tread street radials. I don't race my stock bike. If I did I would lose.)

 

[Nessism]

I'd be curious to know what the maximum suggested pressure was for tires in 1980. I'll bet it was considerably lower than for the tires these days. Thus, I think running higher pressure nowadays is probably fine. I run about 35 and 38 and can notice a big difference (not a good one) if I go as low as the suggestion on the bike sticker.

The manual says 40 psi rear for two-up high speed riding, and the max pressure on GS750guys tire states 41. Pretty close.

Don't think I'd go all the say down to Suzuki's minimum pressure levels even if my riding style matched the criteria. Running at the max doesn't make sense either unless you are riding loaded and at high speed.

 

[Steve]

Tire construction and weight-carrying ability has changed considerably over the years. The tires of yesteryear might have been rated to carry a maximum of X pounds at 32 psi. inflattion pressure. Some of the newer tires might be rated to carry the same weight at 41 psi. Since we don't tend to always run the maximum weight, we shouldn't run maximum pressure, either, but if you used to run 28 psi before, the same pressure would be dangerously under-inflated now. :shock:

One of the best guidelines I have seen concerning tire pressure is to look for a 10% rise when the tire is warm. For example: set the pressure at 30 psi (or your personal favorite pressure). Go for a good ride to warm up the tires. 25 miles of spirited riding should suffice. Check the pressure. If it is less than 33 psi, the tire did not flex enough to warm up and increase the pressure, so drop it about 2 psi before your next ride. If it went up to more than 33 psi, it flexed too much, so add 2 psi before your next ride. Don't adjust pressure until the tire is cold (basically the next day). It may take more that a couple of rides (oh, darn) to get the pressures dialed in, but then you will know what works for your tires and your bike. If you frequently carry a passenger, you will have to do it again, as the additional load of the passenger will require a higher inflation pressure.

.

 

[chuckycheese]

Tires

Tires

I would guess (but, do not pretend to know) that the tire recommendations are more pertinent than the model recommendations, under the circumstances. After all, if you change tires on a car, it can well change the specified air pressure. I think a bike would be the same....and I also think that tires are Waaaaaaaaaaaaaaaaaaay different that they were in 1980.

(I Know I am!!!!!!:-D)

 

[Guest]

Aren't we all.
I run 40 front and rear. I get better gas milege and the tires last a little longer.

 

[bleeble]

I was just thinking about this earlier. 28/32 seems a bit soft to me... although that could just be my saggy fork springs and worthless rear shocks. :roll:

 

[Guest]

GS750GUY here again,
My new Dunlop tires indicate a cold pressure inflation of 41 Lbs on the tire stamp itself for both front an back. However, my manual recommends 38 in the rear and 34 in the front. Which should I go by....the tire or the manual?
GS750Guy

are all the answers confusing enough, gs750guy? :-s

if you want a peace of mind, stay away from the "tire pressure", "what oil", "what petrol", etc type of threads! :-D

experiment a little with the tires' pressure (and suspension settings) and you should find out what works for you in due course

 

[Billy Ricks]

Here is the right way to adjust tire pressure, throw all the other crap out. Check your tires cold before you ride first thing. Then ride for about 10 minutes to heat the tires up. When you recheck you want to see 3 lbs more pressure. If you see more pressure you need a little more air so the tire will run cooler. If you find less than a 3 lb change you are running too much air. That doesn't let the tire get to a good operating temp. I'd be willing to bet if you are running the max pressure stamped on the tire you aren't getting the tire heated properly.

 

[Guest]

sound like an universally applicable procedure
i wonder though whether the ambient temperature plays a part at all

Here is the right way to adjust tire pressure, throw all the other crap out. Check your tires cold before you ride first thing. Then ride for about 10 minutes to heat the tires up. When you recheck you want to see 3 lbs more pressure. If you see more pressure you need a little more air so the tire will run cooler. If you find less than a 3 lb change you are running too much air. That doesn't let the tire get to a good operating temp. I'd be willing to bet if you are running the max pressure stamped on the tire you aren't getting the tire heated properly.

 

[bleeble]

sound like an universally applicable procedure
i wonder though whether the ambient temperature plays a part at all

I would think that both ambient temperature and ground temperature make a difference. IIRC, a 10 degree rise in ambient temps equates to about 2 PSI increase in pressure.

 

[Steve]

Well, I really hate to bring it up, but I'm going to do it anywyay. :-s

One of the best guidelines I have seen concerning tire pressure is to look for a 10% rise when the tire is warm. For example: set the pressure at 30 psi (or your personal favorite pressure). Go for a good ride to warm up the tires. 25 miles of spirited riding should suffice. Check the pressure. If it is less than 33 psi, the tire did not flex enough to warm up and increase the pressure, so drop it about 2 psi before your next ride. If it went up to more than 33 psi, it flexed too much, so add 2 psi before your next ride. Don't adjust pressure until the tire is cold (basically the next day). It may take more that a couple of rides (oh, darn) to get the pressures dialed in, but then you will know what works for your tires and your bike. If you frequently carry a passenger, you will have to do it again, as the additional load of the passenger will require a higher inflation pressure.

And then, just 12 hours later, Billy Ricks posts this as his definitive way. :-s

Here is the right way to adjust tire pressure, throw all the other crap out. Check your tires cold before you ride first thing. Then ride for about 10 minutes to heat the tires up. When you recheck you want to see 3 lbs more pressure. If you see more pressure you need a little more air so the tire will run cooler. If you find less than a 3 lb change you are running too much air. That doesn't let the tire get to a good operating temp. I'd be willing to bet if you are running the max pressure stamped on the tire you aren't getting the tire heated properly.

In my puny little mind it just seems that a 3 psi increase is dangerously close to a 10% increase. Gee, where did I hear that number before?

.

 

[Billy Ricks]

Well, I really hate to bring it up, but I'm going to do it anywyay. :-s
And then, just 12 hours later, Billy Ricks posts this as his definitive way. :-s


In my puny little mind it just seems that a 3 psi increase is dangerously close to a 10% increase. Gee, where did I hear that number before?

.

I never got to your reply before posting mine. It could get critical when running heavy loads at higher pressures. 3 lbs is always what I've seen quoted as the increase you want to see between cold and hot.

And why the attitude? People respond all the time in threads without reading further and finding a similar answer has already been given.

 

[Billy Ricks]

This actually shows you want to see a higher increase but it is on race tires and conditions. No reason it shouldn't carry over to the street though.


http://www.factorypro.com/tech/tire_pressure_risez.html

 

[nert]

One set of tires i bought was the recommended tire model for that manufacturer by application (82 gs1100gl). And they...the manufacturer recommended tire pressures for that model tire on my bike. Thats the way it should be.. They designed the tire, they know the bike, and weights (application determined). So they know best the pressure for their tires. Eliminates guess work, optimizes tire and safety. Now which tire was it??? Maybe check the tire manufacturers web site for your particular bike and tire. (application) To me, a tire manufacturer who provides this information, has done his homework, knows his product, is serious about his product, and earns my purchase support. And as others have stated, the max pressure stamped on the tire is what is needed to support the max load (lbs), also stated on the tire. It is NOT the recommended tire pressure, unless you're actual axle weights are equal to the max weight stamped on the tire.

 

[Steve]

And why the attitude?

Sorry, it wasn't meant as an attitude, but I can see how it came across that way.
I was merely showing that there are many ways to state the same thing. 8-[

In the link in your next post, it approximates the same thing, but looks for a higher pressure increase for track use. I think that if we were to do the 10% or 3 psi increase on the street, then ran the same tires at the same pressures on the track, we would probably see 5-6 psi increase with the additional load of the track, too.

.