motorcycle tyres

[fil]

i am looking for more info than the manufacturers give about the performance of motorcycle tyres
e.g. what testing is required ,what info can the customer ask for ?
etc
unfortunately i am not a mechanical engineer - electronics- but am a quick learner can anyone point me in a direction to start - there appears to be very little testing required for a tyre to be legally sold

many thanks in advance

phil

 

[GregLocock]

I think you are right, there is very little testing that is required. In fact, even for car tires, I don't think there is much. The load and speed ratings indicate what the tire is designed to take, and the SAE specifies minimum puncture resistance for the sidewalls, but the other tests (specified in SAE J341a, J918c, J345a, J161a in my 1976 copy of the SAE handbook) aren't really very onerous.

The reason is that the perfromance of the tire is very application specific, so results given for a black round thing (as they are known) in a generic application would not read across very well.

You might be wondering exactly what drives the design of tires, and I must admit that once you get out of OEM fitment I wonder about that myself. I imagine that fleets have a lot of influence.

Cheers

Greg Locock

 

[fil]

thanks greg,
so how do manufacturers choose a tyre for a bike and why make other tyres which are not oems?
i am getting to the point where i will have to choose another tyre for my bike and would like more info thean 'mine is the best' surely there are some standard tests which will show how stiff the sidewall is or the damping of the tyre etc?

 

[GregLocock]

This is how we do OEM car tyres. Somebody sets a target for the ride and handling for the new model. We build a proto. We try a whole bunch of different tyres on the proto and select the one that seems best (we may pick more than one - eg we want this one's tread pattern, that one's sidewall construction, this one's rolling resistance). then we go to each of the usual vendors and say can you do this, and how much will it cost. Then we work with them through the development process to get to job #1.

Once I had a tyre vendor who came up with a design and asked us to design the suspension around that.

The reason that people make and sell aftermarket tyres is that by the time you've developed a tyre you might as well sell it even if the original user wasn't interested for whatever reason. Also after market tyres don't have to be as balanced as the OEM tyre, so you may be able to achieve better performance in some attributes at a lower cost than the OEM design.

Also some manufacturers buy the old tools from the OEM guys, and then make that tyre elsewhere for the aftermarket or local use. Some companies do this internally - eg third world tire plants may be using 10 year old assembly lines. Cheers

Greg Locock

 

[fil]

greg,
thanks again, so what you are saying is stick to the recommended tyre or try out some others but don't expect improved performance
is it worth getting in touch with the manufacturer to see which came first - the tyre or the bike?

fil

 

[evelrod]

fil---Trying to 'quantify' a motorcycle tire, indeed ANY tire, is like 'quantifying' a race car driver---can't be done! As Greg 'almost put it', selection of the black round things are as much a marketing problem as an engineering problem. More specifically---MOTORCYCLES---
I have owned quite a few motorcycles (except NO Harleys) from 1949 to 1988 (when I stopped riding after at least a million miles) and have had both good and bad tires (obviously). Sticking to the OEM tire is one way of keeping the handling and safety aspect at least equal to what you have (maybe?). In the beginning I did that but, I found that by reading enthusiast mags and observing other riders choices, I was able to get better tires for my applications (cheaper?---Faster?---longer lasting?---whatever!) My personal choice for the safest was the Goodyear 'runflat' tire on my Goldwing. The fastest, best gripping for 'cafe racer' types was Michelin with either Avon or Dunlop (My son swears by Continentals on his BMW) close . The current number of Japanese tires surely must , at least, equal the performance of the Euro tires these days. Competitive markets and the fact that the Japanese have bought out about every body else would indicate to me that they must have comparable tires available. In the vintage racing that I am now involved in just about all the tires are Japanese.
I haven't surrended yet as I am currently looking for a 'deal' on a vintage Norton. When I find what I want I will guarantee it will most probably have the 'best' tire I can find.
---Original Question--- How the heck do you determine what is best? I am going to start reading again and asking local bikers what they use and how they perform for them. I am going to the bike shops and hear what they have to say. I am going to pick from the MAJOR brand names and stay clear of the 'one offs' and 'cheapies'(no WalMart tires for me, thank you very much!) No guarantees I guess but, at least it's a place to start.

Sorry this got a bit 'long winded'.


Rod

 

[GregLocock]

Yes, the OEM tyre is a good place to start. Here's two dirty little secrets, that /probably/ don't apply to motor cycle tyres:

1) Each tyre is measured for balance and force variation. The best tyres go to the OEMs for fitment to new cars. This is typically about 1/2 the production.

2) Once a tyre is no longer an OEM part they can change the construction to make it cheaper, but it still looks the same and has the same load and speed rating. This would especially apply to OEM P&A tyres, where the cost reduction pressure is immense.

Pure personal prejudice: Michelin and Yokohama seem to produce consistently high rating designs, for cars. Michelin in particular seem to have a more scientific attitude than anyone else I've worked with, and have, in the past, had some fairly exotic hardware (and test tracks) put together for tyre testing.
Cheers

Greg Locock

 

[jaiceatltd]

The standard test a tyre industry would perform is

Load endurance test
Speed endurance test
plunger test
contact pressure measurement
deflection test

If you want more details on it.PLease ask me

Jeyakumar
R & D
Ceat Ltd

 

[patprimmer]

I agree with Greg re Michelin and Yokohama, but I have also personally (purely subjective testing) had good results from several model Toyo's. As Rod implies though, good for one guy is not always good for the next, it depends on manner of use, expectations and relaive value put on various characteristics

Regards
pat

 

[fil]

pat
doesn't this mean that the current information given to the general public is insufficient to make an informed choice.
there is info for race tyres but not road tyres, or do they not release it?

many thanks

fil

 

[GregLocock]

No they don't release it. It is a moot point whether they even measure it for most tyres! Leastways, whenever I want a tyre measured they almost always have to do it especially for me.

Cheers

Greg Locock

 

[fil]

so as jeyakumar has said all that is tested is

Load endurance test - over a short time period does it carry the load?

Speed endurance test - over a short period of time will it deform due to speed?

plunger test - can it be punctured by a standard plunger?

contact pressure measurement - for a given pressure it will create a patch of ?

deflection test - does it deflect if hit from the side?

this means that i could make a tyre of the hardest rubber i could find which would last a lifetime of the bike/car and as long as it passes the test i can sell it!
the tyre wouldn't handle but the customer wouldn't know this until he has purchased it and fitted it.

is this enough testing or does the system need changing?

 

[evelrod]

fil, it has been over a year since I have looked at this thread and I see it is still a hot topic. IMO, published information on street tires is inadaquate to determine the choice of tire for some applications. Some degree of guesswork and/or outside influence must be used in choosing, say, a tire for your SUV (The recent Firestone/Bridgestone debacle comes to mind). On the other hand, race tires by defination are ment to perform without undue compromise. Some effort toward this end is accomplished by publishing most (not all) of the design criteria in hopes that race teams will be able to better utilize them. In our society it seems that the "win on Sunday, sell on Monday" is a bit more than a cliche, even if race tires (technology) often do not translate directly to street tires (application).
Since I last posted, I HAVE found that 1948 ex-Bill Young Norton (Four time 1950's Australian Grand Trials champion) and I have mounted my old standby Dunlop K-70 on the rear and an Avon Speedmaster on the front. They are NOT the same as years past but do perform adaquately for my purposes. Emphasis on "MY" !

Caveat emptor !!!

Believe only half of what you see and none of what you hear!

Rod

 

[swall]

My recent Alaska trip convinced me that motorcycle tire selection is a guess .I wore out two tires and put on a third in a 6500 mi. trip. The OEM Bridgestone went 3800 miles.It was replaced in Alaska with a Metzler Tourance;it wore a bald spot in the tread at 3300 mi. (rest of tread still had 3/16" depth). A Duro (Chinese tire) was put on in North Dakota and it went the rest of the way home (1500mi) with no discernible wear. Even though the Duro was a cheapie, I could detect no handling differences,on dry and wet pavement, compared to the other two.My riding buddy put new Michelins on before the trip and they went the entire 6500 miles and still had 1/16" tread depth.His bike was a Kaw KLR 650 and mine a Suzuki DR 650. Similar bikes and identical service but different tire wear.

 

[evelrod]

Hi swall---I like you already. It takes a brave (if not demented) rider to go 6500 on a 650. In Jan. 1980 I went (two up) from L.A. to Mexico City and Central America and back on a Kaw KZ-650 Sport on Michilins and they were still good enough to trade the bike for a Goldwing the DAY I got back!!!

Rod

 

[jf5656]

Almost all motorcycle manufacturers provide a safety advisory regarding a "run-in" period of about 100 miles to allow the rider to become accustom to the feel of the new tire. No hard acceleration, cornering or braking. They also advise against mismatching brands. Is there any support these advisories?

 

[GregLocock]

Absolutely.

On a race car I can see that mixing and matching brands can be useful - worst case is that you'll spin off or roll your car (grin). On the road you don't have room to conduct that sort of experiment.

Running in tyres makes a lot of sense, all the internal plys have to move into their correct position from their as-moulded position.



Cheers

Greg Locock

 

[swall]

I have mixed and matched brands many times, although generally not by choice. I have had problems only when I made a radical departure from the OEM size or tread profile.For example, a Dunlop replacing a same size/profile Metzler front or rear is not a problem.But, I once replaced rounded profile Metzlers with Dunlop K-81's (triangular profile)and turned the bike into a "wobblin gobblin". An oversize rear coupled with a standard size front can also mess up the handling since it jacks up the rear of the bike and changes the rake and trail on the front.I've replaced standard compound rears with sport compound rears of the same size/brand and not had a problem.Ditto for replacing an H-rated rear with a V-rated rear.If I buy a complete set, I will stay with not only the same brand, but also with the recommended front and rear match.It is becoming a real chore to do this due to the profliferation of wheel sizes in the last 10 years as well as the introdcution of radial tires for motorcycles. Many once common sizes,such as 16 inch bias ply front sportbike tires, have become scarce.Finally, the 100 mile break-in not only serves to bed in the tire, but also scrub off the tire mold release on the tread.

 

[evelrod]

To address the "mix and match"---in the classes of racing I have been involved in the rules stipulate the same size all 'round. Not necessarily the same mfgr but even if the sizes were identical, the coumpound variances would coumpound (excuse the pun) any handling problems. Besides, usually we have some contractual agreements with the company whose tires we choose to run. Not disagreeing with you Greg, just adding my "take".

As to "run in"---If I choose to start a race on "stickers" then I can expect the tire to come to operating temp very quickly and give max performance early. I can also expect the temps to continue rising until the tire overheats and grip "goes away"---a one heat cycle tire, as it will not be very good the next cycle. On the other hand If I go out on a new tire and bring it to temp (4 or 5 laps) and let it cool (known as "scrubbing in&quot then the same tire will be good for several heat cycles. The number may vary with tire compound and mfgr. but, all will last several sessions with good grip. Most race tires have an "arrow" indicating which way the tire should be mounted but after the first heat cycle it is somewhat common to run them in any position that is advantageous, based on their circumferance and/or wear patterns. Not necessarily condoned by the mfgr, but, none the less, a common practice. ( I have never had a "tread" unpeel, as it were, with bias tires but I don't practice this on MY radials, but some others do.)

The difference in the tires I chose to put on my antique Norton was a combination of need vs availibility. It was necessary to relace the standard 20 inch wheels of 1948(virtually no tires available) with a 19 rear and a 21 front. The tires were a known quantity from previous use in years past combined with the fact that I am now "two days older than dirt" and I ride rather more conservetively. Mixing brands has always been common practice as 'Swall' indicates. Still, I run in the tires as well as brakes just like I have done all my life, just a habit.

Rod

 

[jf5656]

Has there been any actual testing to support the "run-in" advisories? Do they still use releasing agents? I understood the manufacturers stopped that years ago.