Landracing Forum
Bonneville Salt Flats Discussion => SCTA Rule Questions => Topic started by: bak189 on October 05, 2012, 10:14:01 AM
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Rule 7.B.8......no square edge tires are allowed...Question: What about sidecars? Dunlop makes a special sidecar racing tire with a flat profile (like a car tire) Is this rule only for solo bikes? ..................................................
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I'm pretty sure sidecars are exempt from the no square edge rule.
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Possible.... it should be noted in the rules that sidecar tires are excempt regarding this square edge rule.........................................
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I too am running a sidecar, I'm using a shaved Bridgestone tire and am heading towards 200mph. What is the limit for this tire rule wise?
I have been looking at tires and am confused by M/T front drag tire's description stating they are land speed tires, then under the text, * not for land speed use? Is Goodyear the only LSR tire that can be used above 200mph?
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If the Bridgestones are BT00 series, they should be okay well into the 200's.
I think, and therefore could be wrong, hoping to be corrected, (that) the disclaimer on the M/T tires is for product liability purposes, BUT the tires are okay with the racing organizations over 200.
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The M&H 15 inch front runner tire .....runs on drag funny cars right around 300mph.......right, they are only going 1/4 (or less) but I would think they would be just fine on a 200mph sidecar streamliner.....it is a racing tire...
Do keep in mind that the tire rules for AMA/FIM are somewhat other then SCTA/BNI..........but safety always comes first......................................
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If the Bridgestones are BT00 series, they should be okay well into the 200's.
I would think they would be just fine on a 200mph
Did ya notice the "should" and "think" in those sentences?
Street legal tires have a speed rating. ZR rated tires or V rated that is shaved, are good to 200 MPH. And that's the end of the known speed universe.
Racing tires are good over 200. SCTA says so.
What is the speed rating of a Bridgestone Battlax, Mickey Thompson drag or LSR tire, or Goodyear Eagle Land Speed tire?
Nobody knows. They aren't foolish enough to publish a maximum speed, that I know of.
You know when you accidentally drop a firecracker at your feet and you cringe and turn your head? Racing tires are like that.
The REALLY smart guys running bikes and cars have all chunked tires.
SCTA wants you to shave the tires to reduce the mass, balance the tires for the speed you are going to run, inspect the tires VERY carefully between runs, change the tire if it shows any damage, watch the inflation pressure, etc.
But that's all they can do is ask. There isn't any way to stick a pin in it to nail down what exactly you should run. You get to wear the engineers hat.
Do your best investigation and then put it on the salt dyno.
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Actually, a ZR rating just indicates that they're good for speeds in excess of 149MPH.
Specific ratings include: V = 149MPH, W = 168MPH, Y = 186MPH, and (Y)= over 186MPH
This info is off the Tire Rack website
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Actually, a ZR rating just indicates that they're good for speeds in excess of 149MPH.
Correct, but that's DOT's street rating. SCTA allows them to 200.
(Y) rating is "over 186 mph". Does that mean Bloodhound could run them at 1,000?
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Someone correct me if I am wrong, but front tire chunking has only been a problem since we went to racing tires only above 200. Rear street tires have run to 272 without issue. We don't hear a lot about problems on rear tires lately, so maybe that change is working. Maybe we should be at ZR OK for fronts, racing purposes for rear.
We haven't been running a 200+ bike last several years so I haven't been keeping up
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Front and rear tire chunking pretty much started with the "race" tires. Most of the NA guys are not having any problems with the rear tires. Those that know the throttle works both ways. I think the big HP turbo guys bring lots of rear tires. This was my third season on my race tires.
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Actually, a ZR rating just indicates that they're good for speeds in excess of 149MPH.
Correct, but that's DOT's street rating. SCTA allows them to 200.
(Y) rating is "over 186 mph". Does that mean Bloodhound could run them at 1,000?
You're correct that the ratings I quoted are DOT's and that SCTA rules specify that ZR (and VR) rated tires are good to 200MPH. However, I doubt that SCTA did any actual tire testing to verify that tires with those ratings are good to the speeds quoted in the rules.
"ZR" is actually included as part of the tire size, such as "225ZR45-17", rather than the actual speed rating. The actual speed rating (V, W, Y, etc.) is shown separately, normally after the weight rating, e.g. "86W" (1168 pounds, 168MPH).
The numbers quoted by Tire Rack (or tirespeedratings.org) don't agree with what SCTA shows in the rule book.
Here's what I found:
RATING TIRE RACK SCTA
Q 99 100
S 112 115
T 118 120
U 124 130
H 130 150
VR discontinued 200
ZR >149 200
It looks like SCTA's tire ratings are a bit antiquated. Prior to 1991, the speed ratings were included as part of the tire size. For example, there were SR (112MPH), HR (130MPH), and VR (149MPH). Use of those three has been discontinued. ZR still persists, but only as part of the tire size, and not a speed rating. Since VR has been gone for over 20 years, SCTA may want to give the rules on tires another look.
SCTA's 150MPH rating for H-rated tires is suspect, too. USFRA won't even permit use of H-rated tires on the street cars running in their 150MPH Club.
As for Bloodhound, I doubt if it'll be running under SCTA rules.
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:-D Ok I thought some discussion was needed on the subject and I thank everyone for their input. I find the AMA rule on tires makes good sense, It's your responsibility to select and inspect your own tires. Making hard and fast rules make the rule makers in part responsible. It seems as the SCTA tire rules are more used as guide lines currently(?).
I saw a chunked tire at Bub, a front on a Busa. There were probably 50 others that had no problem with the same tire. So you pays your money and you takes your chances with the rim protectors. IMHO :-D
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Interesting regarding the H rated tires, they are limited to 130 mph in the bike classes.
Dave
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i chunked a front good at WOS on the busa
and Jim blistered a rear on another busa
but both my busa and 750 were fine on the rears this yr
better boost control, lower power levels all made for a much better outcome on the "race" tires than the previous yrs when every good run chunked a rear
but my preference would be to run shaved street tires , they worked well for me this yr at the shootout,
and for Assen last yr when he made many runs over 260mph ,
I keep getting told the change was made because of the problems with street tires and the problem is less now
but is the problem less or just there are less guys pushing the limits at the moment with big hp ??