El MIrage Tires

[typo41]

OK I am really a young pup with land speed racing. We started with running the Brew 102 and now we are running the 28 roadster Salt Circus.

My question concerns land speed tires (tyres for you down under) on the wonderfull crappy silty El Mirage Lake bed. Rule of land speed racing has been narrow tire, small footprint. This appears to work well at Bonneville, long tract and a surface that mostly holds together.

But on the lake bed after the first 25 and the big boys with the 200+ speeds, what is left is rough junk and tachometers that say one speed and a timing slip with another. It seems that the standard LSR tire is just slipping away and not enough run space to overcome. Maybe an almost street tire with some grip will push a vehicle to better speeds and control

I would like to hear from the 'expert's' and other on the merits of narrow smooth compaired to wide almost street tire for some grip on the dirt.

Thanks

[NathanStewart]

The vintage-esq treaded Dunlop racing tires are a good compromise of tall and skinny but treaded for grip.  Plus they've got a much more substantial carcass compared to the GY's that everyone seems to like.  This is beneficial if/when you spin because you wind up lightly scuffing the tread on the Dunlops instead of burning a hole through through your GY's. 

Is your CAIR car making enough power to slip the tires that much that your trap speeds are significantly slower than your indicated tach speed?  Maybe your math is off. 

[typo41]

Nathen, I could give you a good answer if our tach had been working at the time, I love mags, I love mags, but I wish I had a tach that worked with a mag. I was going by what we did on the dyno at the Ferguson's and of course the always right computer spread sheet.
And yes we are running the Dunlops on the roadster, but they are loaner and one day we will have to give them back. Chick did 144+ but we should of had a little more speed. With the tires, gear, and rpm shoulda wooda coulda been 150+

But also we have a vehicle we were working on before the roadster came into our lives.  The roadster is sorta dialed in and I went back to the XO PP truck we have.
Right now it has a set of basic truck tires on the back, but we also have a set of Goodyears. We are looking at 110mph, hopefully. So that is sorta where the question was headed. Use the tread or use the smooth?

Thanks

[jdincau]

This will make your Autometer tach work with a mag.
http://www.summitracing.com/parts/atm-5210/overview/

[will6er]

Tony-

Make sure it will work with your mag. I had to get an adapter from ETC REV LIMITERS;  (307) 856-1637 for my older "Scintilla Vertex" mag.
www.etcrevlimiters.com

[NathanStewart]

Sub 200mph I'd run an appropriately speed rated street tire of sufficient height. 

[jimmy six]

Nathan is correct, however when you start running on a class record is higher than your tire speed limit you must run the correct tire for the record speed not necessary what you are running. Good luck

[jl222]

This will make your Autometer tach work with a mag.
http://www.summitracing.com/parts/atm-5210/overview/

  Make sure you have an ignition switch that will handle the amps from the mag.
 
 We had a mag on the 222 Camaro at one time and when I shifted the engine would shut off. Couldn't figure what was happening. So on one of the runs I kept an eye on the tack and it dropped to zero. We put a big lever type
switch on and problem solved. Can't remember type of switch or mag ''CRS'' but mag was type used on some top fuel cars in the 80's ''Cirrillo'' sp.
 This might not be a problem with other mags.

               JL222

[NathanStewart]

Nathan is correct, however when you start running on a class record is higher than your tire speed limit you must run the correct tire for the record speed not necessary what you are running. Good luck

JD is right but they do issue speed limits now for "under rated" equipment meaning that if the record is 300mph and you're going to maybe go 160, that you don't need the same stuff to go 300 on your 160mph car.  A case like this would probably get a 175mph limit.  Requiring that someone spend all the money for more fire extinguisher, more fire suit, more parachute, and more tire to go waaay slower than the record has kept some folks from coming back and some folks from even showing up.