Landracing Forum
Tech Information => Technical Discussion => Topic started by: Carl Johansson on January 21, 2007, 11:21:27 PM
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a low speed low cc bike - anyone looked at those 12" X 1 1/2" wheels and tires they use on the JR dragsters - I can't seem to find the speed rating on the tires - but I know those JR drags go 80 mph on 5 hp motors!
Carl Johansson
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Part of tire life is a combination of weight and the duraton it is subjected to.
How much does the front end of a JR Dragster weigh and how much time does it spend at 80mph on what kind of surface ?
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scta and bni rules say 15" min on rims unless its a liner or sidecar
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Part of tire life is a combination of weight and the duraton it is subjected to.
How much does the front end of a JR Dragster weigh and how much time does it spend at 80mph on what kind of surface ?
I don't know - but I'm sure it's more weight than would be on my sidecar, but the duration - you have a point there - I'm assuming that these tires need a speed rating - so I'm trying to figure out what that rating is! My thought is ah H rated tire is an H rated tire - or a Z rated is a Z rated - the rating is what is inspected - correct?
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scta and bni rules say 15" min on rims unless its a liner or sidecar
Hense the title - ... wheels for a sidecar!
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Yes, they go by the rating.......unless it states for "Racing Use Only"
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Non rated bicycle tires are in common use on the front of JR Dragsters.
There are special racing tires made for the front at a much higher cost and most of that design is for reduced rolling friction rather that increased speed capability.
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Hey Bak, Can you elaborate on your above statement? They go by rating unless it states for racing purposes only.
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Regarding, "racing only" tires.......I have
Dunlap Vintage racing tires on one of my BSA's .(solo bike,not sidecar)....they have no speed-rating on them it only say "racing" on them.
In addition the Dunlap sidecar racing tires (16 inch wheel) on one of my roadracing sidecars, have the "racing
only" on them.
Some Hoosier tires (13 inch wheel) that we use on roadracing sidecars state: "not for highway use"...............................................................................
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And these pass muster with the tech guys? I'm just curious as it appeared that it was a case of no speed rating, no race.
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According to the SCTA/BNI 2006
Rule Book...............................................
"Production tires with a speed rating of ZR OR SPECIAL TIRES
FOR RACING AS DESIGNATED BY THE MANUFACTURER"
If it states racing on the side of the tire, I would think it would pass SCTA/BNI Tech.
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Regarding tires for bikes that have 18 inch wheels (Vintage)
here is the web-site for tires that
state "racing only" on the side-wall
.........rcbtires.com...................................
no speed rating.....but they are racing tires.
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:-D Could you use go-kart tires that are in common use on enduro karts? The tires are not rated and they are for racing application only. The kart that I used to race was clocked at 147.682 mph at Road Atlanta subject to extreme side loads and hard breaking. The races lasted an hour. I never had a tire failure. :-)
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So you guys are running 16-18" wheels on the sidecar?
Is there any advantage in going to a smaller wheel other than aerodynamic considerations? Are there small, speed rated tires available? I was looking for 10" or so, but the speed ratings are low.
In the SCTA 06 rule book it looks like the photo of the guy in the BMW sidecar has a tiny wheel.
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Since the mid-1980's we have been running a 5 inch wheel on the sidecar using a Goodyear tire.
This tire and wheel has and is being used on the front of Top Fuel Dragsters that go 300mph.
On the "bike" part of the sidecar outfit we run 16 inch front wheel and 15 inch rear wheel.
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Hi Beebe,
There are small mini-roadracers that use H rated tires. :-)
Cheng Shin makes a 3.50-10 CS HI - MAX :lol:
DOT UYBF
4-Ply Rated
430 LB Load rating at 36 psi cold
The tire is tubless but I have tubes in mine and am using steel spoke rims on both my sidecar rigs. 8-)
Terry
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bak189, is that the kart tire we talked about before? Goodyear Bluestreaks? Bridgstones? Burris? Dunlop? They are ALL really good tires rated for racing purposes only but I couldn't guess at any speed rating. :-)
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No the Goodyear tire is not a kart tire......It was developed and made to run on the front of Dragsters in the 1980......"Big Daddy" ran them on the front of his Dragster.......I have been told they do not use
5 inch wheels on the front anymore......something about the way it trips the clocks at the end of the 1/4 mile. I have also been told that Goodyear no longer makes this tire, due to no market
for them ........but there are still some around
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Thanks for the replies guys!
I asked about some Dunlop TT91 10" mini-race tires but nobody knows the speed rating for them??
I was also looking at aircraft wheels, but the smaller ones are only rated at 120mph ground speed.
Hey Terry, is that Cheng Shin H-rated? What's the UYBF stand for? Is there a website or something that has the speed ratings? The only small tires I've seen ratings for were Pirelli's at P-rating.
From what I've seen they have the rating right on the sidewall, but nobody around here has tires in stock to look at and none of the websites have pictures good enough...
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If you use a tire with a DOT speed rating the tire has been tested at far above rated loads for a long period of time.
(http://www.stllabs.com/images/tn_5a.jpg)
We should assume that racing tires have been tested in the same fashion. Even if the tire is branded "racing", all that means is that it isn't DOT rated. What is the maximum speed for that tire? You would have to contact the manufacturer. I have yet to see a speed rating for most racing tires. Despite the racing label, you have to look at the top speed the tire is likely to see in that form of racing.
Goodyear recommends a maximum speed of 300 mph for the Eagle Land Speed tires, but no ratings for the Top Fuel tire.
The killer for tires at high speed is centrifugal force tearing the tire apart. Shaving is a tried and true method to reduce the amount of rubber and centrifugal force on the tire. Smaller diameter is better. Even though the kart tire will be spinning 7,000 rpm at 200 mph it's less likely to come apart.
(http://www.vintagekarts.com/Rockets/McGlashan1.jpg)
In 1980 Australian Rosco McGlashan built and drove a hydrogen peroxide rocket kart that surpassed 253 mph! Rosco has gone 315 mph in a jet dragster and 643 mph in the Aussie Invader 2 rocket car.
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The killer for tires at high speed is centrifugal force tearing the tire apart . . . Smaller diameter is better. Even though the kart tire will be spinning 7,000 rpm at 200 mph it's less likely to come apart.
No. Centrifugal force is proportional to the radius times the square of the RPM. Thus a wheel of half the radius of another, turning at twice the RPM, (giving the same ground speed), will get twice the centrifugal force. Think of a really big wheel, the earth, rotating with a ground speed of 1000 MPH. Not much centrifugal force - you're not noticeably lighter at the equator versus the poles.
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:-D Ah Ha, So what's the answer to why my 20,000 RPM sander throws the 4" dia sanding disks apart but my 2" disks will hang together? :? I still feel certain that a roadracing Kart tire would do just fine at speeds up to 200 mph. Back in the dark ages (late 70's) a friend had a twin engine C-Open Kart that was running 187 mph down the mile long back straight at Garnet, KS. He ran that speed with hard breaking and heavy side loads for an hour + practice. NO tire problems. The tires he was running were Good Year Bluestreaks. There are better tires than that now, so why not use Kart tires? :|
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there is nothing wrong with using them. You dont have to convince us or yourself if they are good enuff... you just have to convince the tech guys!!!! It is a far easier road to sell something that is over built and proven than something that should be good enuff. That said I run the small 8" top fuel tires on my sidecar and never had an eyebrow raised! I think Dean had to jump through a bunch of hoops to get the ok on his cart tire. Do yourself a favor and save tech guestions, get piece of mind, and get the fuel tires! I have found them online, 2 wheels with mounted tires and 2 brand new tires I paid $200.
yours in sport
Kent
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:-D Ah Ha, So what's the answer to why my 20,000 RPM sander throws the 4" dia sanding disks apart but my 2" disks will hang together? :?
Same rpm, twice the radius, twice the centrifugal force. Why the :??
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:-D Ah Ha, So what's the answer to why my 20,000 RPM sander throws the 4" dia sanding disks apart but my 2" disks will hang together? :?
Same rpm, twice the radius, twice the centrifugal force. Why the :??
If both were wheels with the same ground speed the RPM would be quite something else between them .
If the construction methods and materials were the same I bet I could predict the outcome.