What's the deal with these darn 33's?

D

Digindeep

New member
Just can't seem to figure this tire situation. We ran supremely well this past saturday afternoon. Our 55's were biting well during the afternoon hours. As night fell upon us, much cooler and the dew...we thought the right move was to switch out for the 33's. What a mistake, like being on ice. What the heck!!! Thought we preped well during the week and prior to taking the track. Are they just too old? Any thoughts?

21/2 - 3 on tread depth, sticking 52-55 on the durometer.
Thanks.
 
Unless it rains while you're at the track (Hunterstown) with no returning sunshine, 55's are pretty much the only choice punching over 50 on the duro. The track was slick, but not near enough deep moisture to make a 33 work. I've seen the track sloppy wet numerous times before practice starts, but the surface only takes a few classes, wind, and moderate sunlight to make 33's feel like you're on ice.

Scottie
 
I've seen that happen at OVRP before. 33/55 rule, tried sneaking 33s on my light driver she was all over the place sliding through the corners slowest kart on the track. Put 55s on the next week, maybe 3pts harder on durometer at most, fastest kart in 2nd round practice and heats. That stiffer sidewall makes a big difference.
 
The 33's are probably rolling over, like KKania said, the stiffer sidewalls of the 55's makes a big difference
 
Thanks guy's, thanks to the many fine people on here and around us, we're learning fast. Air pressure varies...33's we go around 5 in and 5.5 out...55s somewhere around 6 and 6.5.
 
If you are talking about hunterstown, we were also there. Used same 55's from practice through last feature. Track kept picking up speed all night. Track was too hard for 33's and that's why you were sliding like on ice. We did the same thing with 33's the prior week in practice and slid all over track.
 
Digindeep said:
Thanks guy's, thanks to the many fine people on here and around us, we're learning fast. Air pressure varies...33's we go around 5 in and 5.5 out...55s somewhere around 6 and 6.5.
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I have just started getting on 33's and I have not been able to go that low on 33's at all.. I have found air to be my best friend with the 33.
 
c.doxee "Wish they would make the 33's with 55's side wall!!!" Wanna know a little secret? They have the same sidewall! The rim width (10") that most of you run takes bite out of the tire so then you put chemicals and/or drop the air pressure to get it back. lol Obviously its all about combination y'all have painted yourself into a corner. :)
 
So putting it on a narrower rim will help Mike? I have always thought the 44's and 55's had a stiffer sidewall, they sure do feel stiffer when you compare them
 
The sidewall construction might be the same, but the spring rate is significantly different between a 33 and 55.
Typically if dirt racers are on a 55, they've externally prepped the contact patch only down in duro to what the track calls for (or even that similar of a 33 (50-52d)) and maintain the stiffer sidewalls to gain roll speed on higher biting and big momentum tracks.

-----
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cuts
www.CarlsonMotorsports.com
Celebrating 25 years of service to the karting industry
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Burris Racing said:
c.doxee "Wish they would make the 33's with 55's side wall!!!" Wanna know a little secret? They have the same sidewall! The rim width (10") that most of you run takes bite out of the tire so then you put chemicals and/or drop the air pressure to get it back. lol Obviously its all about combination y'all have painted yourself into a corner. :)
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Hahahah We are Trolling ourselves. I love it! Looks like I got some more testing to do this spring! I appreciate that little tid bit Team Burris!
 
Just an FYI, but the "spring rate" thing has come and gone a long time ago simply because it was a vague term or better yet a variable that changes dynamically due to several ongoing changes tires go through with use. Statically the spring rate might appear different in a new 33 over the 55 because the rubber in the 55 is harder so it is less flexible giving the sidewall the appearance of being stiffer. Once the tires get used (or cut and/or prepped) that all changes.

Mike
 
My question would be how is this 33 only rule gonna work at the burris money series, especially when the track bites up real good? Isn't it going to kill the tires?
 
Mike, while I agree that spring rates change with tire usage, (they certainly do - the guys forced to run Maxxis ELs are well aware of this) be certain that the 55 has a higher spring rate than the 33s for the reason you gave (rubber duro.)
Things as simple as wheel widths, air pressure, internal preps, and the profile of the cut (shoulder thickness especially) will change the spring rate of the tire dramatically.

Spring rates (at least on right side tires) are very much still part of the equation (especially when competitors are restricted to a single brand & single compound rule like with the 33 only tracks.) Just one reason you see guys purchase new tires, then let them sit for a year to harden up before cutting half of the rubber off of them.
Spring rates is not a "vague term." It's a quantified measurement.
 
ddracing28 said:
My question would be how is this 33 only rule gonna work at the burris money series, especially when the track bites up real good? Isn't it going to kill the tires?
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We have tested the ss33a on a Yamaha for 20 laps brand new with just sticker removed and showed very little wear. At the shippensburg race the kart that won the 33 only class said the tires wore about the same as a 55 just had to let off and not over drive the tire.

Keith
Burris Money Series
 
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