My Vredestein vs Kenda Rambligns- Part II

All,

Just a quick run down on my Vredestein rear tire installation. Installed a 205/60R15 on the back. Started at 18 PSI, will work the 4 lb. rule. Much smoother than the Kenda. The Kenda I took off required 12 wheel weights, the Vredestein used 3. I like specs, so please don't bash me for posting this. It may be insightful to some other new guy.

Vredestein 205/60R15 Specs as measured by me not installed.
Diameter (Inch) 24.625
Circumference (Inch) (Tape Measure) 77.75
Section width (Inch) 8.8
Tread width (contact patch) (Inch) 6.75
Weight (Lbs ± 1/4 lb) 18.625
Load Rating 91V (1356 lbs) @149 MPH (at max sidewall of 51 PSI)
Tread 2 Ply Steel, 1 Ply Polyester, 1 Ply Polymids
Sidewall 1 Ply Polyester

Kenda 225/50R15 Specs as measured by me not installed.
Diameter (Inch) 24.00
Circumference (Inch) (Tape Measure) 75.25
Section width (Inch) 9
Tread width (contact patch) (Inch) 7.75
Weight (Lbs ± 1/4 lb) 21.25
Load Rating 76H (892lbs) @ 130 MPH (at max sidewall pressure of 30 PSI
Tread 2 Ply Steel, 1 Ply Polyester
Sidewall 1 Ply Polyester

Speedometer error was around 2.8% @ 70 MPH (2 MPH) with the OEM Kenda, the new 60 series Vredestein reduced that by half to about 1.4% @ 70 MPH (1 MPH).

Odometer error was odd. The original Kenda had the odometer mileage showing .3% less than the GPS, but with the new, larger Vredestein the mileage got more off, the odometer showing 1.2% less than the GPS. Funny the odometer being almost spot on while the speed was almost 3% in error before the new tire was installed.

On a side note, there was some concern about ride harshness due to the V (or H) rating making the sidewall stiffer. The Vredestein sidewall was more supple than the Kenda, possibly a function of the 60 series vs the OEM 50 series.

I was very disappointed in the rear tire installation to find that the rear rim and wheel bearings are made in China. The pulley was made in USA though!

Yeah, you'da thunk that if they were dialing in an error, they'd at least make it the same for both speedo & odo/trip meter, wouldn't you?! :dontknow: But NO! They make sure the Speedo reads optimisticly so they comply with the National/International Standards, but then fix the odo/trip meter so it's bloody near spot on - and of course that screws up any real chance you ever had of making them BOTH read fairly accurately!! :gaah: Or maybe that's WHY they do it!! :rolleyes:

Thanks for the installation info & specs comparison..... Now all we want is feedback on how the Vredesteins ryde, perform, & wear. :dontknow:

Could you just duck out & rack up saaay 10,000 miles on them for us, and come back to us with your analysis of how you think they've handled over that milage, as well as including full braking, slalom, & cornering analysis plus tire wear rates & ambient temps, tire pressures/temps, & tread temp readings for each 100 mile session?!? What's today.... 16th of May?? Sooo, you can get that back to us by Friday 31th of May can't you thanks, but if you don't think you can squeeze it in, then I'm sure someone else will......... :shocked:

:joke: Sorry, I just hadta! :shemademe_smilie: :shemademe_smilie: :roflblack:

Mr. Aawen,

I'm in the middle of tire testing and am confused, to say the least. The 4 PSI rule is kicking my butt. I started the rear out at 18 PSI, just because I didn't want to do many iterations of the boring and redundant test patterns. The rear plumped up to a satisfying and comfortable 21.5 PSI, so 18 PSI cold is good enough for me.

The fronts are what is giving me fits. I started at 20 PSI, they both went to 22 PSI. Lowered them the second time to 18 PSI, they both went to 20 PSI. Lowered them again to 16 PSI for the third test, the both went to 18 PSI. At 16 PSI there is a clear radial bulge in the sidewall, and you can see the contact patch is all the way across, almost looks like the sidewall is coming into play. Yet no more than marginal temperature increase. Any thoughts on this? I'm at the lowest pressure that I'd like to see in this tire, and it rides exceptional smooth at 16 PSI, with the front at 18 PSI. I don't want to use them as run flats with no air, but I'd at least like to know physics still works in my neck of the woods.

Another questions is, once you select a pressure for the unladen weight, and refine it for the laden weight, whether you use a single combined pressure (like auto manufacturers usually do) of dual laden/unladen pressures, how do you (or do you?) adjust for temperature changes. 10°F per 1 PSI, so lets say you're doing testing on a 90° F ambient day and come up with, say 16 PSI in the front tires. Fast forward to winter (Hey, the Vredesteins are ice rated, wonder if they're studdable?) and you're looking at 20° F. Do you simply set the tires at 16 PSI to get the same effect? Then bleed the air out again as the summer warms up?

Physics always works if you can quantify the inputs and measure the resulting changes including all energy. The rear wheel will always build more heat and therefore pressure than the front tires due to the input of Mechanical Energy of the engine driving the wheel. The 4 psi "rule of thumb" does not trump the Law of Conservation of Energy.

Probably the main reason the fronts heat up less is there are four sidewalls supporting lateral and radial forces, compared to only two sidewalls doing the same in the rear regardless of construction and profile........ Your ryde, your choice :yes:

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Originally Posted by AeroPilot

Physics always works if you can quantify the inputs and measure the resulting changes including all energy. The rear wheel will always build more heat and therefore pressure than the front tires due to the input of Mechanical Energy of the engine driving the wheel. The 4 psi "rule of thumb" does not trump the Law of Conservation of Energy.

Probably the main reason the fronts heat up less is there are four sidewalls supporting lateral and radial forces, compared to only two sidewalls doing the same in the rear regardless of construction and profile........ Your ryde, your choice :yes:

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:clap::clap: …………. I think we have a very, very reasonable answer to this issue..... If there is one thing I've learned over the years is " appearances can be deceiving " ….. I remember waaaaaaaaaaaaaaaaaaaaaay back when …. the RADIAL tire was becoming more popular …. folks were way over pressuring them because they looked Flat compared to BIAS ply tires ….. the Important thing is - how flat is the Tread to the road surface …. In this comparison the Radial wins , what the sidewall looks like can fool you into thinking it needs more air , in reality not so …… jmho ….. Mike :ohyea:

H0gr1der, if you are happy with your front tires at 16 psi and they are only increasing pressure by 2psi, you can certainly continue to ryde on them like that, just be aware that you might be compromising some aspects of your tires performance & ability to do their job properly. Tread wear, puncture resistance, overall traction, and likely hydro-planing resistance on wet roads are just some things that come to mind which may be less than ideal, but how measureable that difference will be, I don't think anyone could tell you with any degree of certainty, and regardless, the 16 psi in that tire on your Spyder for the way you ryde and in the conditions you are riding in is going to be better than any pressure that's a 'one size suits most' pressure on a placard that was intended for an entirely different tire anyway, or than a pressure that increases by less than 4psi after an hours ryding. That said, I am currently running slightly larger tires on the front of my RT at 14 to 16psi depending upon the conditions, load, or ryding I'm about to do and I pretty reliably get the 4psi increase that the '4psi rule of thumb' calls for. But you might be ryding in colder weather and on colder roads, you might ryde slower or with less stress on your tires than I do, as others have mentioned, there are hundreds of variables that may make a difference, but the rule of thumb is simply a repeatable & measureable way of taking into account all those things and getting your tires as close to their ideal pressure as any 'Joe Public type rider can manage readily - and all you need is a reliably consistent tire pressure gauge & the ability to use it! Still, I don't think there are many tires or riders out there that should be running at anything much lower than about 14psi - that's certainly as low as I'm prepared to go for normal highway ryding, altho there have been and likely still will be the odd occasion/conditions where I'll drop my front tires down to 8 or 10psi for a bit, but it will only be if the surface I'm ryding on is soft or slippery enough to warrant it and even then I'll certainly be keeping my speed down and all control inputs gentle - and the pressures that low will only be as long as is absolutely necessary!

When it comes to your rear tire, yes, it is going to be working harder cos it's the single drive tire, but it's also a tire with somewhat more volume of air inside it as well as being proprtionally larger & more heavily constructed than your front tires, so while it will need more air inside to do what's being asked of it, it's not usually a much greater amount. I generally run something between 14 to 16 psi in my fronts, and usually something between 16 to 18 in my rear tire, altho on hot road surfaces &/or when we are ryding loaded and 2 up, I might go as high as 20 or possibly even 22 if the roads have been baking in the sun for a few weeks. But the 4psi rule still applies - the greater volume of air & the heavier tire construction as a result of the bigger tire make it still applicable - and remember, this 4psi rule may be something you've only heard about recently, but it's not something I just plucked out of the air, it's something that has been around for a long time now, helping a whole lot of people get the best from their tires over many millions of miles!

As for Physics always working, that's absolutely correct, and this '4psi rule, a 'rule of thumb' always takes all the rules of physics and all the many variables you've just encountered over the last hour of your riding into account, because they are what makes the pressure in your tire go up by 4psi or 2 psi or 26 psi! You can't escape the physics of it all, it applies all the time (unless you know something I don't yet!) Sure, if you want to measure all the variables that might make a difference, take all the readings and then do all the calculations that result in a more exact pressure, you could do that, altho it might take you a day or more plus a shed load of expensive gear too, each & every time you want to go ryding! But remember, this '4psi rule' is a 'rule of thumb'; and as such it is something that has proven over many years and millions of miles to get pretty damn close to the optimum pressure each & every time, and a whole lot easier too! For those who may not understand the term 'rule of thumb', here it is as defined by google seach:

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rule of thumb

/ˌruːl əv ˈθʌm/

phrase of rule

a broadly accurate guide or principle, based on practice rather than theory.

"a useful rule of thumb is that about 10 hours will be needed to analyse each hour of recorded data"

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I've found over quite a few years of using this rule & doing this, that most driver/riders who practise & use the 4psi rule over a few weeks to get the hang of it properly can then just check their pressures & the increase after an hours drive once a week or so, or if they don't ride that often, maybe once a month or so if that suits them better. And once they get a little practiced with it thru use, most get pretty good at estimating what pressures will work for todays weather & road conditions & loads & their intended ryding style. Yes, you will probably want to use a (slightly) different pressure for summertime or wintertime; you'll probably want to use a different cold start pressure if you are heading out on a 500 mile ryde on the Freeway to what you'd use on a 200 mile ryde on the back roads & byways; and you'll almost certainly want to use a different pressure if it's pouring with rain or hotter & dryer than a dead dingo's donga - but for most, it doesn't take a heap of practice to start getting better at recognising what is likely to make a difference to them and their best pressure, nor does it take that long to check their tire pressures, and the more you do it the better you'll get at working out what's right for today's drive/ride! And you'll get better at recognising the different feel & handling you get from a tire that's not anywhere near the right pressure too! Besides, if you aren't changing your ryding style or load all that much, the difference in pressure between road surfaces or weather conditions probably isn't likely to be all that much - maybe a couple of psi. However, sustained high speed driving/ryding is likely to make your tires run hot, so you'll probably want to go for a bit more of a higher pressure for that than you'd use just tooling around the back blocks - maybe 4psi or so, possibly even more if you are fully loaded/ryding flat chat!

So NO, it's not a do once & forget thing! Just like the weather changes & we all get older, you'll probably want to check your tires fairly regularly for a while, at least until you are comfortable with the range of pressures that's working and close to right for you, but like I said, most who do bother using this rule of thumb fairly quickly learn what pressure's going to be pretty close for the ryding they are facing today! And once you know what cold start pressures you are using for this season/load/particular trip, you probably only need to check them in an hour if there's a significant change in one or more of those many variables that do make a difference! Btw, the more effort & care you put in to looking after your tires & running the right pressures, the longer your tires will last and the better they can do their job of looking after you!

Sorry about the epic saga again, but you did ask, and it's a complex thing, even if the 4psi rule of thumb tries to make easier for the average driver/rider to use - and it's been proven to work over many years & for many millions of miles thru it's practical application so that YOU don't hafta bother with all those variables and rules of physics or calculations etc etc etc...... but if you don't want to bother - it's your ryde, your life, & your tires; no-one else is ryding, living, or wearing them out for you! :thumbup:

Thanks Peter great info ………...However IMHO … unless you are Racing for serious Money …. it's really of little or no consequences …. you close enough to the IDEAL ( and that is a very time consuming practice ) to be Extremely safe in your operation …… Mike :ohyea:

You are pretty much right Mike. The range of pressures that're 'right' for most of us isn't really all that wide or different, I mean, seriously, how much difference in load can you realistically put on a Spyder & still ryde - it's not as tho the difference there is going to be thousands of pounds, is it?! And it really won't make all that much difference if someone is using the top end of the range rather than the bottom end of the range or even the exact middle, I really doubt very much that many of us could even detect many of the differences that'll produce in the ride, tire wear rates, or handling parameters, etc. Close enough to ideal can certainly be close enough for many! :thumbup:

But as a quick aside, just like you wrote earlier regarding 'appearances can be deceiving' there is the possibility that the 'bum dyno' that's been mentioned before can also be deceiving!! What you 'feel' is right might not be! Some people can become mislead by fixating on just one or maybe a couple of aspects of the whole gamut of things tire pressures can affect - direct steering is a good example. If you really like sharp & precise steering response & you almost always drive on good surfaces in the dry, increasing your tire pressures well outside that 'close enough to ideal' range can give you the feel you want, a snappy response to every steering input, making your steering really easy to turn especially when you're going slow, and probably even getting you marginally better fuel economy; but going too far out of that 'close enough to ideal' range of pressures might feel great in terms of response, but it's because your tires are so hard they will have less ability to absorb road shocks & mold over any irregularities in the road surface, your ride will be harsher than it needs to be even if you think it's OK on the good stuff, you will be working your suspension harder, and you will almost certainly wearing out the centre of your tire's tread significantly quicker than the edges (altho the very edge on each side may be scrubbing thru the turns) and you won't have the whole face of the tread on the road ever!! But it'll probably FEEL good if that's all you want from your tires! And that's one really good reason that everyone should use either the 4psi rule (of thumb) or something similar every now and then to check that they are still somewhere in that 'close enough to ideal' range with their tire pressures. Btw, I generally feel that +/- 2psi on either side of that 4psi ideal increase is close enough for most - very few readily available & useful tire pressure gauges will be able to measure much closer than that anyway, and besides, it's going to be SOOO much better for each & every individual rider than the 'one size fits most' pressures recommended by the vehicle manufacturer, especially if you are no longer running the OE Spec tires! :ohyea:

Back to tire pressures - there are a fair few different methods that people can use to get their tire pressures into the right range. They can follow advice from other people, like many do on a forum, but then may never know if that recommendation is right for THEM & the range of variables in their ryding. Or they can wet or chalk their tire's tread face & examine the pattern that leaves on the road, but they really should do that for every ambient temp & load condition variation they will ever ryde in/under, and even then it won't necessarily take into account the different speeds &/or ryding styles they may use at different times when ryding. And there are other tools or methods people can use to get their tire pressures into the right ball-park. Or they can simply use the 4psi rule that responds to all the variables they just experienced in their last hour of ryding in order to give them a pretty good idea of how close they really are to that ideal for the next lot of ryding facing them, and over time they'll probably learn (thru checking every now & then) how things like different ambient temps, road temps & condition, loads, ryding styles etc does change their ideal pressure & gradually get better at picking the best cold start pressure for today & today's ryde! But you are correct in saying that once you've used whatever method you choose to get into the 'close enough to ideal' range for you & your ryding, loads, style etc, that once again, you're going to be so much better off than the person relying on the 'one size suits most' pressure the manufacturer recommended for a different tire that it won't really make a great deal of difference if you're not exactly at the 'right' pressure now, will it?!........ :clap:

But what if some of you did feel that getting close to ideal was really worthwhile and you chose to persist a little more and get really good at doing this 4psi thing - TPMS & FOBO or similar systems can make it fairly easy to keep an eye on your tire pressures, & once you know what to watch out for, it doesn't usually take many all that long to work out what pressure differences different temps, speeds, loads, or road surfaces are likely to make, and it's easy enough to check your pressures when you start out cold & then again an hour or so later when you are ryding every now & then. It's not a religion that is unforgiving if you don't do it every time you ryde! Do it a little more often for a few weeks or a month or so just to cement the process & changes in your mind, then just use it to check how close you are every now and then! Who knows, you might be able to get significantly better tire life than you've ever managed before, or maybe you'll get noticeably better handling and ride, or maybe you'll even find that you can take the twisties more readily, faster, & yet still comfortably without waking the Nanny or having to work so hard!! The more effort you put into getting your tire pressures right & looking after your tires, the better they'll be able to look after you! Isn't that worth at least the bother of giving it a go?! It's all up to each of YOU - and just like you do Mike, I'm just trying to help a little if I can! :2thumbs:

Peter you HELP A LOT :clap: ….. I love reading ( and learning ) your soliloquys :roflblack: …. When I was an LEO - I learned that keeping it simple worked better than just about anything …. KISS principle …. You and I have talked about the tire pressure thing for years already …. and WE have pretty much agreed the with Auto tires 14 to 17 lbs for the front and 16 to 19 lbs for the rear is going to work for 85% of the owners …. As an example, I use a K&N air filter, it works for me …. I have never even considered doing flow charts to see EXACTLY what is going on ….. To me when the difference is Life & Death I take notice , otherwise really close to ideal - to me is close enough …… And your " bum dyno " is what I used to call " Butt Theory " ...…… close enough :thumbup::roflblack:...……….Mike :ohyea:

Mike and Peter, Thank you both for all the valuable information you provide. I have learned a lot. My uneducated observations are: I think the Spyder is more sensitive to tire pressures than 2W motorcycles due to having 3 tires tracking and effects of centrifugal force (or lack of). For the last 3 seasons, we have toured extensively and in very different climates and altitudes. When we start touring, our ambient "cold" temperature is 95-100F. We ride in that for a couple of days in altitudes from 1,500 to 8,000 FT. Then we will tour for 2-3 weeks with ambient temperatures "cold" of 60-65F and much closer to sea level. During this touring period I find that I need to add about 2psi. Then when coming home and back into the high desert, I find that I need to remove those 2psi to keep the tires where I like them. Guess I'm getting anal. But, my "bum dyno" can feel the difference. And I smile more when everything just feels right. Thanks again for sharing your expertise..... Jim