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/cgi-bin/YaBB.pl General Category >> The Cafe >> tire pressure /cgi-bin/YaBB.pl?num=1363478530 Message started by rl153 on 03/16/13 at 17:02:10 |
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Title: tire pressure Post by rl153 on 03/16/13 at 17:02:10 I filled my rear tire , by mistake to 46psi and rode for a couple miles.Could it have blown out,or is that not that bad? thanks |
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Title: Re: tire pressure Post by Serowbot on 03/16/13 at 18:11:06 It's nothing... 80 or 100psi might be another story... 46 is just firm... I've started running mine a little low... (in the 20's)... roads here are so bad,.. it just really helps absorb the shocks... It's almost worse than off-roading... ;D... |
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Title: Re: tire pressure Post by Gyrobob on 03/16/13 at 19:18:06 7563746971646972060 wrote:
Truth. Good. Also, keep in mind the pressure number on the sidewall means less than nothing. It is one of those mindless nanny-state things. The numbers that are useful, at least to start off with, are the numbers in the manual and on the bike itself. From those numbers, go higher if you want a rougher ride and longer tread life and cooler running tires,.... go lower if you want more traction in some situations, a softer ride, less tread life, and sidewall flex (with pressures really low) that will heat up the tires and weaken the sidewalls. |
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Title: Re: tire pressure Post by WD on 03/16/13 at 20:53:17 I tend to run my tires within 5 psi of sidewall max. 46 psi would be in the 10% over category for well made mc tires. You're fine, just bleed it down to around 40 psi for better response to steering inputs versus the stock recommendation. The bike manufacturers have you run at 2/3-3/4 max inflation to compensate for... get this... the compromise shocks they install at the factory. ;D With the factory pressures my 98 Savage always felt like it wallowed through corners instead of tracking through corners. Running how I have for the last decade, it actually is capable of pretty decent entry/exit speeds. |
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Title: Re: tire pressure Post by Serowbot on 03/16/13 at 22:20:31 I've actually wondered about this, recently... I know,.. proper tire inflation is important... ... but,... like I said,... I'm runnin' low, on purpose, because the roads here, suck!... ... but,... Running by the rulebook (even though, I do like to carve the canyons),... has given me consistent, center wear... ... and I wonder, even with the additional heat, and friction,... if I won't get more miles by running a little low, and having the addition tread contact?... I may have just talked myself into believing this theory... ;D... ... but, even if it costs me few,... it is way more comfy,.. and there is the added traction... I'm 140lbs wet,... (the bike don't know I'm on there)(and my bike is at least 50lbs underweight)... So, I'm running... 450 or 460lbs, fully loaded... I've actually ridden' for weeks with less than 15lbs of air, and not noticed... :-[... PS... an overinflated tire, will pop a lot easier, on a hard edge... like a curb, or jagged rock, etc... I'm rambin' again... :-?... |
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Title: Re: tire pressure Post by WD on 03/17/13 at 02:59:21 At 240# plus the bike, the stock inflation pressure always seemed low. My small truck is the same way, stock inflation it's all over the road, tires inflated to 40 psi it steers a whole lot better. My full sized truck calls for 36 psi f/r, handles a lot better with the tires at 50 psi... manual steering. |
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Title: Re: tire pressure Post by Greg on 03/17/13 at 07:26:54 My bike was feeling kinda scary in turns. Like I slip a little. I finally checked the air pressure and they were at 15 and 16. Filled them up to 36 each and it feels normal again. |
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Title: Re: tire pressure Post by Boofer on 03/18/13 at 00:58:34 Serowbot, A low tire pressure will eventually cause "Blocking", a condition where you can run your hand smothly in one direction but it hangs up on the tread when rubbed in the opposite direction. This is tire wear that is perpendicular to the tread, not along it. Each section of tread wears from front to back or vice versa. A tire is constructed to push against obstacles from the inside out, so more pressure prevents tire damage better than one with a saggy sidewall. An over inflated tire will wear the tread in the center and underinflation will cause excess wear on the outsides of the tread. Low inflation also gives a mushy "push" through curves. Since our tires have such a low amount of air, unlike a car, a few pounds make a big difference in handling. I know you are experienced enough to find a happy medium between comfor and safety. As for the bad roads, most states have them, so I can relate. :) |
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Title: Re: tire pressure Post by Dave on 03/18/13 at 04:42:03 Too low of tire pressure can also allow the tube to pinch between the road and rim when you hit a pothole or something with an abrubt edge. Trials motocycles only run 4 pounds of air in the rear tire and they have switched to tubless tires to eliminate the pinching of the tube at the rim. |
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Title: Re: tire pressure Post by spacepirates on 03/18/13 at 09:50:54 Also to be considered is the fuel economy associated with high/low tire pressures. Generally, higher pressures will give better fuel economy, whereas lower pressures will give you better grip. Each to a certain point in a given situation, mind you. Running at 100 psi isn't going to give you fantastic MPG just like running at 0 isn't going to make your tires grip like racing slicks on a hot day. I generally keep my tires between 30 and 40, but as long as I don't notice them feeling different, I don't check tire pressure more often than oil changes. that might not be the best rule to follow though.... You should see what tires are initially "inflated" to to get them seated on the rim. a LOT more than 46psi. of course, the tire being mounted isn't on a bike going 60mph hitting a pothole with a sizeable adult riding.... |
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Title: Re: tire pressure Post by Pine on 03/18/13 at 10:33:37 I watched a guy go down ... due to low tire pressure. The "theory" was everything was fine till we hit some really nice S curves and under that sidways load the front "rolled" ... wobble wobble.. down he went. I now have a very small pancake air pump right next to the bike with the tire air chuck and pressure guage.. ZERO excuss not to check and correct. I put the pressure to side wall spec, which seems mighty stiff for our roads, but meh. |
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Title: Re: tire pressure Post by Gyrobob on 03/18/13 at 16:36:45 1407430 wrote:
The sidewall numbers are arbitrary fabrications that have nothing to do wih actual usage. |
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Title: Re: tire pressure Post by Gyrobob on 03/18/13 at 16:40:35 4B72757E6F74691B0 wrote:
The number on the sidewall is not a spec. It is an arbitrary number pulled out of some Fed's ass. It means nothing. Nothing. If you feel like you want to use some sort of "spec" then use the numbers printed on the bike or in the manual,.. then go from there as you desire. At least the numbers printed on the bike are pulled out of an engineer's ass. |
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Title: Re: tire pressure Post by Dave on 03/19/13 at 05:00:45 6F515A474A474A280 wrote:
The sidewall numbers are arbitrary fabrications that have nothing to do wih actual usage.[/quote] The numbers on the sidewal do have some meaning.....It is the pressure that should be in the tire at the rated maximum load. If you have less of a load than the pressure should be reduced as well. |
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Title: Re: tire pressure Post by rl153 on 03/19/13 at 10:55:47 what about on a car, should you go by the door sticker ,even if you have replaced your tires with another brand? |
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Title: Re: tire pressure Post by Serowbot on 03/19/13 at 11:23:45 60697A6562693D3E35350C0 wrote:
Yup,... needed tire pressure is based on weight... same tires on two different cars will require different pressures... A #300 pound rider on a Savage should have a little more air in his tires, than a #100 pound rider... |
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Title: Re: tire pressure Post by Greg on 03/19/13 at 12:36:17 2F26352A2D2672717A7A430 wrote:
No. Definitely not. The best way to determine the correct air pressure in a car is to draw a line across the tire with a piece of chalk and move the vehicle a short distance. Add or release air until the chalk line wears evenly. You may actually find for optimum tire wear and traction all four tires may have different pressures. edit: I must admit, I only did this for my Jeep. My car gets 36 psi cold in all 4 regardless of the tire brand. Call it laziness. |
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Title: Re: tire pressure Post by rfw2003 on 03/19/13 at 13:34:58 696C6B60676D0E0 wrote:
No. Definitely not. The best way to determine the correct air pressure in a car is to draw a line across the tire with a piece of chalk and move the vehicle a short distance. Add or release air until the chalk line wears evenly. You may actually find for optimum tire wear and traction all four tires may have different pressures. edit: I must admit, I only did this for my Jeep. My car gets 36 psi cold in all 4 regardless of the tire brand. Call it laziness.[/quote] Yup this is the only way to correctly set the pressure that I know of. I do this for all my 4 wheeled vehicles when they get new tires and most of the time it's different then what the tires were on before even if it was the same brand/model tire. R.F. |
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Title: Re: tire pressure Post by rl153 on 03/19/13 at 13:42:42 The chalk idea seems good,how far do you go to see the wear?. Also,I have read that you should fill the tires 10% less than the max tire pressure, which is different on some tires. |
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Title: Re: tire pressure Post by Greg on 03/19/13 at 14:09:38 I would just roll down the driveway. You don't want it to disappear, just see what is going on. Less than 100 feet. |
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Title: Re: tire pressure Post by rfw2003 on 03/19/13 at 14:17:56 on most surfaces it just takes a few revolutions of the tire to get a good wear line to show on the fresh chalk |
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Title: Re: tire pressure Post by Greg on 03/19/13 at 16:17:15 32263772707073400 wrote:
You are correct. I guess my finger did a double tap. It should have read 10 feet. :-[ |
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Title: Re: tire pressure Post by Gyrobob on 03/27/13 at 05:16:52 33080512030F141209010C13600 wrote:
The sidewall numbers are arbitrary fabrications that have nothing to do wih actual usage.[/quote] The numbers on the sidewal do have some meaning.....It is the pressure that should be in the tire at the rated maximum load. If you have less of a load than the pressure should be reduced as well.[/quote] Wrong. That "rated maximum load" is not an engineer's number, it is a bureaucrat's number. The correct tire pressure is whatever work best under usage, and the numbers in the manual, or on the stickers the feds require on the vehicle are much closer to reasonable. The bureaucrat's number is usually way higher than what would be a typical load, and the pressure they assign to it makes the tire rock hard. |
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Title: Re: tire pressure Post by Dave on 03/27/13 at 09:19:24 1F212A373A373A580 wrote:
The sidewall numbers are arbitrary fabrications that have nothing to do wih actual usage.[/quote] The numbers on the sidewal do have some meaning.....It is the pressure that should be in the tire at the rated maximum load. If you have less of a load than the pressure should be reduced as well.[/quote] Wrong. That "rated maximum load" is not an engineer's number, it is a bureaucrat's number. The correct tire pressure is whatever work best under usage, and the numbers in the manual, or on the stickers the feds require on the vehicle are much closer to reasonable. The bureaucrat's number is usually way higher than what would be a typical load, and the pressure they assign to it makes the tire rock hard.[/quote] GYROBOB......This might just be a topic you and I aren't going to agree on.......I am not going to believe the connection of the sidewall tire pressure and a bureaucrat? I do believe that it is necessary for some labeling of the tire with a maximum load and a maximum pressure - or else users won't have a clue what they can or can't do with that tire. I just prefer to believe those numbers are etablished by engineers and not politicians. Here is some supporting data from one knowledgable source....which was not written by a Bureaucrat. And just about every tire manufacturer or distributor states that the pressure listed on the tire is the recommended pressure at the maximum load rating of the tire. And just about everyone that monkeys around with cars or motorcycle knows that this is not the pressure to use when adjusting your tire pressure. Every vehicle should have a manufacturer recommended tire inflation value, usually on a sticker on the driver's side door jamb. This figure is determined by the manufacturer based upon the vehicles stock weight distribution, wheel and tire size. This is probably the best value to use if it applies. However, if you have changed wheels, tires, or weight significantly, this number may not be appropriate. Also, it is sometimes unclear as to what were the assumptions used to determine those pressures. For example on a pickup or SUV, they often list a much higher rear than front tire pressure. This is likely a pressure setting at the maximum vehicle load ratingm so on a 1/2 ton pickup, for example, thise would be with approx. 1000 lbs. or cargo in the bed. With little or no bed load, this "factory" tire pressure may be too high, so take those numbers with a grain of salt. Tires, too, come with manufacturer-specified inflation specifications. These, however, are not vehicle specific, but rather refer to the maximum inflation pressure the tire can handle in relation to its maximum load carrying capacity. For example, assume you have a light truck tire with a 2500 pound maximum load rating at 50 PSI air pressure. Lets say there are four of these tires mounted on a 5000 pound vehicle (with 50/50 weight distribution), so the per-tire load is 1250 pounds (5000/4). Clearly, the tire is nowhere near its maximum load, in fact it is at 1/2 load in this case. A case could be made for inflating the tire to 1/2 its maximum pressure (25 PSI in this case) based upon the load on the tire. Actually, while there is a fairly linear relationship between a tire's inflation pressure and its load carrying capacity, it is simply not a straight line from 0 to the maximum load. I did a least-squares-fit analysis on some pressure vs. load data for a series of agricultural tires and found that the following factors seem to fit the data quite well: mL = maximum tire Load (lbs) mI = maximum tire Inflation (psi) L = the actual load on the tire (lbs) L = 0.21*mL + (0.79*mL/mI)*inflation Here is the link for the source of the above....You can find more by just searching the internet. http://www.4crawler.com/Diesel/Tires.shtml#ProperInflation |
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Title: Re: tire pressure Post by justin_o_guy2 on 03/27/13 at 09:44:17 OHHH the obviousness! Its never even occurred to me that there could be a way to "see" the inflation on a tire. Chalk! Coolniss! & Now, Im wondering, what would happen if a guy wet the cement? No chalk, just looking at how the tire presses the water away? I know for sure you can use water on cement to check for some types of frame damage on a car. Ive done that. Now? Im gettin some chalk, man,, thanks guys. |
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Title: Re: tire pressure Post by Dave on 03/27/13 at 10:44:13 2F3036312C2B1A2A1A22303C77450 wrote:
When I was autocrossing we would use white shoe polish. We were not adjusting for even tire wear - we were looking to see how far the tire would roll over onto the sidewall. The idea was to adjust the tire pressure so that the tire would just barely stay within the tread and not roll too far over onto the edge or sidewall - this would give the most useable footprint area without damaging the sidewalls. If you put too much air in the tread contact patch is reduced and the traction would suffer. If you have some leftover white shoe polish from your Pat Boone look alike days......you might try that! |
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Title: Re: tire pressure Post by Gyrobob on 03/29/13 at 04:46:36 No one in his right mind would ever operate a motorcycle tire based on the sidewall pressure anyway,.. so discussing sidewall pressures is mootish. Pretty much the same with cage tires. The "rated maximum pressure" shown on the sidewalls is a worthless number. Operate any vehicle at those tire pressures and it will feel like there are no tires at all, just metal wheels contacting the road. The tires will wear out in the middle inch or two of the tread in short order,... and the traction situation will scare you. If you are too lazy or just don't understand all this, and you want to use someone else's numbers, use the vehicle manufacturer's numbers in the vehicle owners manual which usually are the same numbers on a sticker placed somewhere on the vehicle. They are closer to reality. The most sensible way to set tire pressure from a wear and performance standpoint is to use some of the suggestions in previous comments that use various methods find out what actually works. |
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Title: Re: tire pressure Post by Ed L. on 03/29/13 at 18:50:11 I alway look at the sidewall pressure on a tire as a starting point, once set you go out and run the bike, car, truck as you plan to drive. If it doesn't seem right jack the pressures around and try it again. How it handles is a personal choice which can be adjusted by fine tuning tire pressure. |
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Title: Re: tire pressure Post by Dane Allen on 03/29/13 at 20:37:46 2B3D2A372F3A372C580 wrote:
Yup,... needed tire pressure is based on weight... same tires on two different cars will require different pressures... A #300 pound rider on a Savage should have a little more air in his tires, than a #100 pound rider...[/quote] What approximately would you think the pressure for the front tire be for someone closer to 270? |
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Title: Re: tire pressure Post by SALB on 03/29/13 at 20:44:48 MAXIMUM tire pressure is the highest pressure that the engineers at the tire company have determined is safe to operate. (As per government mandate) It is best to start with the vehicle manufacturer's recommendation, and go up as load increases. If you find yourself going past the weight or psi on the sidewall, then you need to either reduce your load, or upgrade to a tire with a higher load rating. In other words, it's a more precise way to measure load ratings, improve safety, and protect the tire company from people installing the wrong tires on their rigs. Sorry no bureaucrats were implicated in this post. ;D |
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Title: Re: tire pressure Post by Serowbot on 03/29/13 at 21:55:26 486D62694D606069620C0 wrote:
Yup,... needed tire pressure is based on weight... same tires on two different cars will require different pressures... A #300 pound rider on a Savage should have a little more air in his tires, than a #100 pound rider...[/quote] What approximately would you think the pressure for the front tire be for someone closer to 270?[/quote] I'd go with 32 to 34lbs... (for better mpg's on smooth road,.. try 36... if your roads suck, like mine, try 30lbs)... Yer' a big fella'... I'm going about 26 to 28lbs... 'cause I'm a squirt... and my roads suck... :-?... Higher pressure will give better mpg's, but a hard ride... Lower pressures will give more traction, and a softer ride... With car tires,... proper inflation gives more tire life,... but, on a bike that is of less consequence... because bikes will wear out out the center strip... ...unless you can ride like Rossi... I run my car 4lbs under... because I mostly drive alone, or with only one light passenger... .. and the roads,.. suck!... What I lose in thread life, I gain in suspension components...(a harsh ride will wreck ball joints and bearings, etc... even light biulbs)... Just keep decent air in your tires,.. and the rest is simply trading one advantage for the other... Balance comfort, traction, handling, MPG, and tire and suspension component wear... Easy as toast... :-?... Okay,.. not as easy as toast... :-?... 32 to 34lbs is a good starting point ... |
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Title: Re: tire pressure Post by rfw2003 on 03/29/13 at 22:06:52 I've got a question here for motorcycle tires since they have a rounded contact patch and not a big flat contact area. I'm used to doing the chalk line method on cages and most other types of vehicles that have the large contact areas with the ground to adjust the tire pressure to find out the optimum pressure for the given parameters of my normal load. Can this method still be used on a motorcycle tire, if so how much of a contact patch should I be looking for on the 140/90 rear tire and the stock 100/90 front tire of the savage? I'm using the Route 66 tires currently but when those wear out I'll most likely get the Metzeler ME 880 Marathon tires so I have a much longer lasting tire that still has great grip. BTY I'm down to about 225 and most of my riding is solo, but every now and then I do 2up with my daughter and she weighs in around 140. If you need to know I also have the progressive shocks 11" model 412-4233C 115/155lb installed as well. I still need to change out the Fork oil for 20wt from what Lancer has told me, but I've been avoiding that as I'm not really wanting to tear down my front end just yet. Now if they made a better progressive spring for putting in there it just might give me the nudge to do that, but all I've found is the Ryca one that stiffens it up to much from what I've heard, for every day riding comfort. Also I may need to add the roads around here SUCK, as I'm sure JOG can verify since we live fairly close to each other. Any advise is well appreciated. TIA R.F. |
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Title: Re: tire pressure Post by Serowbot on 03/29/13 at 22:18:45 rfw,... read my previous post... Chalk is useless on a bike... Chalk will check for even contact,.. and bikes don't do that... You are a bit heavier than average,.. add a couple of lbs to what the bike recommends,.. and work from there.. Add a bit for riding 2 up,... take off a bit for crappy roads... Adjust by gut,... and butt... ;D... JMHO... disclaimer... :-?... |
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Title: Re: tire pressure Post by rfw2003 on 03/29/13 at 22:39:35 6274637E66737E65110 wrote:
I did Serow, and that's what I was kinda figuring. That's why I asked to just to be sure. I didn't worry about it much years ago when I was riding because my riding back then was mostly off road. Now my riding is all on-road, so tire life is very important. I'll give the few lbs over the stickers a shot and adjust from there to see how she feels. Won't be able to find out this week, as we have storms predicted all week long :'( but hopefully after that we have some good weather again and I can get some good riding in. |
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Title: Re: tire pressure Post by houstonbofh on 03/29/13 at 22:56:48 Here is how to really find the right pressure for a bike. http://www.spacerjim.com/Customizing_your_tire_pressure.pdf It kinda works for cars as well. It adjusts for your weight, and the way you drive. |
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Title: Re: tire pressure Post by Serowbot on 03/29/13 at 23:23:20 Tire makers want you to run the air that will give the best tire life... Car makers want your luxury car to feel smooth,.. or your economy car to get their estimated mpg's... Whatever... everybody has their agenda... Ride yer' own ride... ... as long as your tire pressure is between 20lbs and 50lbs... it ain't gonna' change yer' life... Lower than 20lbs,.. you could slip the tire on the rim,.. and cut your valve stem, or pinch the tube... Higher than 50lbs, you could blow on a pothole or curb... The rest is up to you... not the tire company or bike maker... Everyone has an agenda,.. but, it's your bike... Bike tires wear out so fast,.. nothing else really matters... The center patch will go before you use up the tread... ... and the sidewalls will rot away,.. before you any damage running low... The difference in the life of a tire, is a couple of thousand miles either way... I'd rather get new tires,... than replace bearings, or fork seals, shocks,... even frames can crack, if you hardtail... or limit fork travel... If the tire pressure is harsh to you,.. it's twice as harsh to your bike... ... but,.. if your tire pressure has you squirrly on the road,.. it's a danger... Less math,... more gut... :P... JMHO... PS... semi trivial trivia... Those nuts on your valve stem,... are for installation purposes only... they aren't supposed to be tightened down after install... (even mechanics tighten them down)... They should be screwed up, to mate with cap after install... this allows a tiny bit of shift before the valve is decapitated,... in the case of rim slip... :-?... |
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