Tire Pressure

[Flapjack]

Figured it might be good to start a new thread based on the conversation in the vee brand tire thread.

I noticed quite a few mentioned running 42 in the rear (based on tire rating at max). Someone else brought up a curved scale for psi and max weight, good thought, is there one?

Personally, I have Pirelli Night Dragon tires front and rear. Max on front is 42 with 761 lbs, rear is 50 at 1019 lbs. I've been running 34 up front and 38 in rear. 66% of riding is solo (170 lbs), 33% 2 up (add 130lbs for gf) plus anything in saddle bags, call it 20lbs max.

Maybe should add the suspension settings to this as well, they somewhat go together. I leave mine at 3 on the dial and 20 psi for the air.

What do you run? What are you weights? Thoughts behind it all?

[OldSchool]

There are many different opinions as to what is right, what is wrong, what works and what doesn't. Just like with tire wear , when one rider gets 2 and 3 times the tire life than another one does. Pretty much its common sense as to what is best for any one rider. All the factors go into tire wear: tire pressure, weight of riders, climate , road conditions and material roads are made of and even the compound of the rubber the tire is made of. It is near to impossible to come up with a generic " one size fits most" formula for tire wear and use. Softer rubber compound in tires will wear much faster than a harder compound but will also grip the road like glue. To offset the accelerated wear the softer tires get, it helps to increase the tire pressures, but not so high that it cancels out the gripping aspect of the tires. Harder tires reverse by going with lower pressures but not to the point it cancels out the extra wear they get. Mix in all the factors above and a 250 lb rider in Florida will have a totally different experience than a 250 lb rider in Minnesota will.

[andyvh1959]

If 34 psi in the front and 38 psi in the rear works for your riding style and you don't notice abnormal tire wear (cupping/scalloping, uneven wear off center) then you have the pressures figured out. Many riders assume tire wear issues are road crown/shifting/braking/shaft vs chain drive/riding style caused. Those factors have little impact really. It comes down to tire pressure and load/heat. Too many riders pay little attention to tire pressure, and ride around on tires probably 10 to 20 psi too low and think nothing of it. Same for load. They figure "Its a big bike so load it up." But, every bike has a recommended load limit (GVWR) which few riders are even aware of. My 94 BMW has more load capacity (550lbs) than most new Harleys (some barely over 400lbs). Suspension and shocks too have a lot of impact on tire wear. Most shocks at 20,000 miles are just springs with no damping control. Once damping is gone, tire cupping wear goes up significantly.

Best to start with higher air pressure and adjust it down till you find that blend of wear, feel and capacity. Nothing eats up tires quicker than heat and load, and nothing heats up tires better than low pressure. For bikes like our Vulcans if you don't know the actual load of your weight (in full riding gear), passenger weight, accessory/load weight, I'd never run pressure lower than 35 psi front or rear. For your numbers, you and your passenger are pretty light really, so 34/38 frt/rear may work fine for you.

[Tortuga]

I respectfully disagree about crowned roads. I lived and rode NE roads for many years and miles and tires wore on the left side all the time with the high crowned roads...very common. It's also hard to imagine that regular hard cornering has no effect. Likewise, hard acceleration.

[MAS Tequila]

It’s not crowned roads.

It’s distance traveled while turning.

Lefts cover more ground and rights cover less.

Simple math.

[VulcanJeff]

What he said ^^^^

This cupping issue has been discussed on here before I think. Someone posted a link to an article that refutes the crowned road theory. It was convincing and changed my mind. Maybe I can find it and repost...

[Chuck A.]

Yes I want to read it myself. Crowned road with a bike sitting straight up, Only commend sense that the left side of the tire will wear more. It touches the surface more when riding in a straight line. My tires stay cupped. Mas Tequila has seen me ride in the Carolina mountains. Soft side edge they build into the tire don't have a chance around a good curvy road.

[VulcanJeff]

http://www.rattlebars.com/tirewear/index.html

[andyvh1959]

The only proof of the crowned road idea would have to come from countries with long roads where the riding is on the left lane, like Australia. If enough riders from Aussie land comments similarly to those here in the states I might believe it more. I feel though, that road crown is only a contributor, not the main cause. I would more believe it is a combination of load, low tire pressure, inadequate suspension damping than road crown.

Another possible contributor to the road crown affect is countersteering. If the road has sufficient crown that to release our hands from the grips would cause the bike to track off lane to the right, would give reason to constantly/slightly countersteer onto the left grip to maintain the intended line. Do that over thousands of miles and it could justify the road crown affect. A road crowned to the right would require a slight, but constant, lean to the left. That, combined with inadequate suspension damping create constant flexing of the tread edges on the leading edge of the tread pattern, which leads to cupping/scalloping of the tread.

[MAS Tequila]

If you are still not convinced that increased mileage is what causes one sided tire wear on the front tire of motorcycles, you'll have to come up with a theory that satisfies all of the evidentiary criteria. A) It will have to explain the fact that when riding upright, the tire's side wear bands do not contact the pavement (road crown, unbalanced/off center bike weight and even wheel misalignment won't work). B) It will have to reverse itself in countries where one rides on the left side of the road rather than the right (road crown still sounds plausible here but it was eliminated in "A" above).
In the case of right side driving countries like the USA, one does indeed ride farther on the left side of the tire than on the right side of the tire. At a simple single lane intersection that is common in most residential neighborhoods, negotiating a left turn will have you traveling TWICE the distance that you do making a right hand turn. That's at a simple single lane intersection. A double lane will have you making four times the distance. But even when you are confronted with nothing more than a left curving road, the radius of that left turner will be larger than if you were coming the other way on the same road making a right around that same curve. If you don't believe this, check out the How Stuff Works web site about your car's DIFFERENTIAL and why it's called a differential (your shaft driven two wheeled motorcycle does not have a differential, it has instead a "final drive" which drives only one wheel). Also note that Olympic runners start in different locations because the outside runners must run farther to the finish line. ((click for reason -- Click for pic)
Besides the fact that the left radius is larger which means you will probably go faster causing more stress on your tire than you would going the other way, there is more visibility when making lefts than rights which will add to your tendency to make the turn faster as well. Failure to negotiate a left turn will have you going off the the road onto the shoulder or into a ditch. Failure to negotiate a right turn will have you crossing into opposing traffic. Though neither scenario is appealing, there is a subliminal advantage to left turns (riding shoulders and ditches is better than crashing into trucks head on) and this will have you going a bit faster on lefties too.
The increased radius on left turns means more distance is traveled turning left than turning right on the average riding day. That is plane geometry and plainly undeniable. Because of the natural tendency to make left turns faster (admittedly this is subjective and open to debate, but is plausible for reasons given) there will be more stress placed on your tires as they travel that longer left distance. Increased left side tire wear is evident, though, on both the front and rear tires but because the front tire shows less evidence of flat band center wear (which disguises the side wear bands on the rear tire), side wear is more evident to the eye up front and leaves you to wonder, "Why does the left sideâ€* of my front tire wear out first?" Now you know.

[BrokeAss]

^^^^^ yup!!! ^^^^^

[DragonLady58]

Originally Posted by MAS Tequila

If you are still not convinced that increased mileage is what causes one sided tire wear on the front tire of motorcycles, you'll have to come up with a theory that satisfies all of the evidentiary criteria. A) It will have to explain the fact that when riding upright, the tire's side wear bands do not contact the pavement (road crown, unbalanced/off center bike weight and even wheel misalignment won't work). B) It will have to reverse itself in countries where one rides on the left side of the road rather than the right (road crown still sounds plausible here but it was eliminated in "A" above).
In the case of right side driving countries like the USA, one does indeed ride farther on the left side of the tire than on the right side of the tire. At a simple single lane intersection that is common in most residential neighborhoods, negotiating a left turn will have you traveling TWICE the distance that you do making a right hand turn. That's at a simple single lane intersection. A double lane will have you making four times the distance. But even when you are confronted with nothing more than a left curving road, the radius of that left turner will be larger than if you were coming the other way on the same road making a right around that same curve. If you don't believe this, check out the How Stuff Works web site about your car's DIFFERENTIAL and why it's called a differential (your shaft driven two wheeled motorcycle does not have a differential, it has instead a "final drive" which drives only one wheel). Also note that Olympic runners start in different locations because the outside runners must run farther to the finish line. ((click for reason -- Click for pic)
Besides the fact that the left radius is larger which means you will probably go faster causing more stress on your tire than you would going the other way, there is more visibility when making lefts than rights which will add to your tendency to make the turn faster as well. Failure to negotiate a left turn will have you going off the the road onto the shoulder or into a ditch. Failure to negotiate a right turn will have you crossing into opposing traffic. Though neither scenario is appealing, there is a subliminal advantage to left turns (riding shoulders and ditches is better than crashing into trucks head on) and this will have you going a bit faster on lefties too.
The increased radius on left turns means more distance is traveled turning left than turning right on the average riding day. That is plane geometry and plainly undeniable. Because of the natural tendency to make left turns faster (admittedly this is subjective and open to debate, but is plausible for reasons given) there will be more stress placed on your tires as they travel that longer left distance. Increased left side tire wear is evident, though, on both the front and rear tires but because the front tire shows less evidence of flat band center wear (which disguises the side wear bands on the rear tire), side wear is more evident to the eye up front and leaves you to wonder, "Why does the left sideâ€* of my front tire wear out first?" Now you know.

That makes sense! Now, should I be worried that it does??????

[MAS Tequila]

That makes sense! Now, should I be worried that it does??????
__________________


Be very afraid!!!

[usranger74]

I had a 07 Nomad. I ride solo. On trips my total wt approached 325 lbs. I kept both tires at 42 PSI. I do the dame with my Goldwing. I put approx 40,000 miles on the Nomad. I live in NE and ride a lot in "flat land". Never had a issue with cupping.