Cobra Tire Modifications on Dirt

Chuck D17

Member
For those running Cobra Tires on Dirt, what are you doing to them if anything ? I'm being told they need nothing done to them, no cutting, no prep. If that's true that would be most welcomed but I'm skeptical.

I'm thinking a light scuff w/220 grit on a belt sander and that's it.

Interested to hear from people actually running them what they're doing to them.

Thanks for the input !
 

jaymancds

Premium User
For those running Cobra Tires on Dirt, what are you doing to them if anything ? I'm being told they need nothing done to them, no cutting, no prep. If that's true that would be most welcomed but I'm skeptical.

I'm thinking a light scuff w/220 grit on a belt sander and that's it.

Interested to hear from people actually running them what they're doing to them.

Thanks for the input !
I sand them, and only do external prep. The set I rolled turned into goo. I have gone through 3 sets of them this year. My only complaint is I have to flip them more often than my maxxis.
 

Chuck D17

Member
I sand them, and only do external prep. The set I rolled turned into goo. I have gone through 3 sets of them this year. My only complaint is I have to flip them more often than my maxxis.

If you're willing to say, what prep are you using ?
 

Kj26

Member
I sand them, and only do external prep. The set I rolled turned into goo. I have gone through 3 sets of them this year. My only complaint is I have to flip them more often than my maxxis.
Rolled internal or external and with what to turn them into goo ?
 

jaymancds

Premium User
If you're willing to say, what prep are you using ?
Rolled internal or external and with what to turn them into goo ?
Disclaimer, Im not an expert, this is just what has been working for me.


The set that turned to goo was rolled with Nall's blue internal, and had a combination of Nalls green, yellow, and purple used on it externally at different times. They would never harden back up, and then eventually were duroing in the upper teens low 20s. Theyve been sitting since the first week of june, still arent harder than 40.

What I have been using with some good success is a mixture of FMS Green and Perfection Extreme Green. The Extreme green is pretty thick, and somewhat oily, so I cut it with the FMS green to get it a bit thinner. This combo has gotten me my first win, and 4 top 3s including two heat wins, and a second place Saturday night. As the evening falls between the heats and features I will wipe a round or two of Bubbas Concept red, and then hit the track with the tires wet with that green combo.

I'm willing to help everybody, even if it is to my detriment ;)
 

Kj26

Member
Ok thanks. The set we won (400) and finished 2nd (350) with 2 weeks ago had 60cc internal with bite wiped on the outside. I shoulda softened them up a tad to get em to fire faster, but I didn’t and that was a day race with a hard track.
I’m not sure how much you flip your Maxxis, but I flip our Vegas every 2 races and it looks like the Cobras will be on the same rotation.
 

jaymancds

Premium User
Ok thanks. The set we won (400) and finished 2nd (350) with 2 weeks ago had 60cc internal with bite wiped on the outside. I shoulda softened them up a tad to get em to fire faster, but I didn’t and that was a day race with a hard track.
I’m not sure how much you flip your Maxxis, but I flip our Vegas every 2 races and it looks like the Cobras will be on the same rotation.
So far I have gotten between 3 and 4 races on the maxxis, and I'm flipping cobras either every race, or every other race depending on how the track was.
 

Kj26

Member
Yea with as soft as your running them I can see doing it weekly. I’ll run the Vegas 2 races flip, 2 more flip, 1 and dismount to the forsale pile.
 

Kj26

Member
For those running Cobra Tires on Dirt, what are you doing to them if anything ? I'm being told they need nothing done to them, no cutting, no prep. If that's true that would be most welcomed but I'm skeptical.

I'm thinking a light scuff w/220 grit on a belt sander and that's it.

Interested to hear from people actually running them what they're doing to them.

Thanks for the input !

Chuck I’m sanding with 240. I’ll be at Caroga Saturday, I’m thinking with the slower speeds of the predator you won’t have to do much. We’ll be running FH 375 & Clone 360.
 

OVALTECH1

Premium User
I have 3 sets. Two are untouched just a 220 cross hatch and go the last is 220 crosshatched and I have put some trac tac orange prw or diamond on them. It dropped them roughly 10 points in duro. I love em and win with them great tire for the money.
 

1fasttiller

Member
We ran 2 heats and 2 features with a new set out of the wrapper last week, Definitely feathered up the inside of the Rights. I'm thinking they will need flipped about every 2 races and this was only Jr2. Bad fast tire out of the wrapper though with NOTHING rolled internally. Only light wipes of some tracktac stuff on the outside before hitting the track. I plan to buy more and definitely get some rolled to see how they respond.
 

Slack2014

Member
*****shared direct from cobra******

How about a little tech talk!?

Haven't tried the Cobra yet but are thinking about it? Here's a little info on the Cobras to help get you started... enjoy!

"Cobras are unique and can't be prepared in the same manner as other tires. Just like you can't prep a Maxxis the same way you prep a Burris tire and you can't prep a Vega tire the same way you prep a Hoosier tire. Cobras can't be treated the same way as other tires. The rubber compound is unique and so is it's construction. This will help you better understand how to successfully prepare your Cobra Racing Tires for a successful night at the track.

Construction
You can easily feel the weight difference between Cobra tires and other race tires. It is lighter because of the way it is constructed. With 0.070" of tread, the Cobra still has plenty of rubber to get the job done. The lighter weight provides faster acceleration and roll speed but doesn't compromise corner speed.

Mounting
Mounting the Cobra requires no special tools or methods outside of normal means. You'll find the Cobra mounts easily and quickly.

Inside Prepping
The first rule to prepping a Cobra tire is DO NOT inside prep them. Cobra tires are fresh from the factory when you get them and does not need additional chemicals inside to make the tire "work." If you choose to inside roll Cobra tires, you'll find that the tire is very fast for about three laps and then lap times begin to fall off. That makes for a great qualifying tire but if you want it to last throughout a race, we recommend not to inside prep the Cobra.
An advantage to not inside prepping (besides saving time and money) is that the tire's rubber is consistent throughout from inside to outside. That means during a race that has multiple caution flags, the Cobra will refire each time the green flag drops again. On long green flag runs, laptime falloff of a properly prepared Cobra is almost nonexistent.

Outside Prepping
As we've pointed out, Cobras are fresh tires and fresh tires already make their own grip. You may enhance that to meet the needs of the track surface you race on by adding chemicals to increase grip or condition the tire.
It may take some experimentation to determine exactly what the Cobra needs at your home track but as a rule of thumb, we recommend using half of what you normally use. For example, if you prep with two wipes of Prep "A" for one week prior to an event, prep Cobras with one wipe instead. Go easy with the prep, it doesn't take much. Like every other tire out there, if you over prep the Cobra, it will either be fast for a few laps and then slow down or it may simply be slow throughout the duration of the race. If the tire feathers, you've used to much prep. On hard tracks, do not prep the Cobra - mount it and go.

Chassis and Air Pressure
The chassis setup and air pressure is fairly consistent with other tire manufacturers but may need some slight tweaking to find that "sweet spot" your Cobras need. For reference, if you normally use Maxxis tires, increase crossweight by one percent and air pressure by one half of a pound when using Cobra tires.

Sizing
Need the perfect circumference? Cobra tires size extremely easy and they stay there. When sizing tires, gone are hours spent in tire warmers with a crazy amount of air in the tire. If sizing is new to you, read through the steps and the more you do it, the easier it gets!

Growing a Cobra
To grow the circumference of a Cobra, determine what size the tire needs to be. Inflate the tire until it is one quarter inch larger than the ideal size you need (if you need a 34" tire, simply inflate the tire until it is 34.25" in size). Next place the tire in an already-heated tire warmer or hot box. Some racers use a propane torch to heat tires but they're dangerous and we don't recommend using one. Leave the tire in the warmer or box for 30 minutes MAXIMUM. Cobras can stretch easily and quickly and have the ability to grow as large as 35" or more so be careful with the length of time the tire is in the heat source. Remove the tire from the heat source and allow it to cool to room temperature, usually about thirty minutes. Once cool, reduce the air pressure to the race pressure you intend to race on. Measure the tire. Usually, it's dead on. If not, repeat the procedure.

Shrinking a Cobra
Yes, Cobras shrink easily, too! If you have a tire that is too large in circumference, again you're going to need a heat source (warmer or hot box) and a five gallon bucket of ice water. First step, remove the valve core from the valve stem in the wheel. Second, put the tire in the heat source and heat the tire until the tire and wheel assembly is hot. Third, (you have to move fast!) while the tire is hot (use a towel to hold the tire and wheel to keep from burning yourself) quickly squeeze all of the air out of the tire and (IMPORTANT!) replace the valve core in the valve stem. The tire should be squished down pretty tight and then immediately... Fourth, dunk the tire and wheel assembly in the bucket of ice water. Keep moving the tire in the ice water to evenly shock and cool the hot tire causing it to shrink. Once the tire and wheel are ice cold, remove it from the ice water and allow it to warm back to room temperature. Once it's back to room temp, slowly inflate the tire to race pressure. Wait two minutes, recheck the pressure, and then measure it. Repeat if necessary.

Once you've reached the perfect size, whether shrinking or growing, we recommend storing right side tires at eight psi, the left front at racing pressure you normally use, and the left rear tire uninflated. This usually keeps the stagger consistent. You may need to tweak this formula, but do what works best for you.

Surfacing
You can surface Cobra Tires using an angle grinder or tire surfacer, whatever works best for you. We recommend 120 grit (or finer) to just knock the smooth surface off of the tire to give it a surface to accept prep (if you choose) and removes the glazed surface.

Balancing
A balanced tire is faster than an unbalanced tire. There's no doubt about that. We recommend balancing your tires for optimal performance.

We hope this has provided some insight that will help you get going with your Cobra Tires. If you have questions, contact us through our website at www.cobratires.com."
 

ohv60racr

Member
I have 3 sets. Two are untouched just a 220 cross hatch and go the last is 220 crosshatched and I have put some trac tac orange prw or diamond on them. It dropped them roughly 10 points in duro. I love em and win with them great tire for the money.
How many races have you been getting out of them ?
 

OVALTECH1

Premium User
I ran all season on them on a really abrasive track surface and they still have decent tread thickness. They just seem to fall off a bit in between race days.
 

"J'-remy

Member
I heard they don't hold air well and sizing them is difficult because they keep changing all over the place. any truth to any of that?
 

jaymancds

Premium User
I heard they don't hold air well and sizing them is difficult because they keep changing all over the place. any truth to any of that?
They hold air fine. Sizing can be tricky because they stretch very quickly. Personally, I had to really watch staggers between races (every other week) especially the left sides. Seemed like they would vary a lot week to week. Between races I would leave my rights at about 20psi just to be sure they weren't shrinking.
 

Kj26

Member
They are like a Burris between races, put 10# in the rights and let the air outta the left rear week to week and you‘ll be fine. That’s why I love Vegas, one heat cycle and they barely move.
 

1fasttiller

Member
They definitely size easily! 40 psi and a few mins in the box and mine were at almost 35"!

LOL They shrink pretty easily too though. Overall good tire!
 
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