Tire Pressures

[Daniel Morency]

My Family autocrosses predominantly with Dunlop DBS tires... at 70 to 80 degree temperatures what would most people reccommend for tire pressures. We typically run 10 in front and 12 in the rear.

Thanks

Dan

[Bob Monday]

The Dunlop DBS is a fairly hard tire. It's usually used by "beginner/novice" classes or budget-minded classes in W2W racing. My brief Google search turned up the following durometer comparisons to the Hoosier kart tire:

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http://www.carlsonmotorsports.com/HoosierTire.HTM

Below is a chart of durometer numbers measured on OUR durometer....keep in mind that your durometer may measure differently (higher or lower) but can be used as a good baseline for comparison.

Hoosier D10 = 34d Burris SS-11 = 36d
Hoosier D20 = 45d Burris SS-22 = 42d
Hoosier D30 = 52d Burris SS-33 = 55d
Hoosier D40 = 65d Burris SS-33 = 68d
Hoosier D50 = 70d Firestone YGF, Dunlop DBS = 60d
Maxxis DK-3 = 70d
Hoosier A40 = 65d Maxxis HT-3 = 76d
Hoosier A55 = 75d Maxxis HG-3 = 78d
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That would make it comparable to the MG Red! (Durometer sequence for MG: Green, Yellow, Orange, Red). To answer your specific question, my recommendation would be to reduce the air pressure to zero... then dismount the tires and replace them with a MUCH softer tire! For a comparison, the autocross-popular MG Green durometers at about a 46.

If you retain the DBS, there's no way that you're going to be competitive with anyone that has even a semi-serious F125 effort. Not only will you have no grip, but you'll not begin to heat them up on a typical (~1-minute) autcross course, even moer so at the relatively low air temperatures you reference. The good news is that you'll never wear them out. I guess that's good news.

Use them for lapping, getting some seat time, but not autocross unless you have no alternative. Or pay for shipping and I'll send you a couple sets of used Greens (2-3 heat cycles). (Seriously: contact me through the "Contacts" page of the glskusa.com web site if interested.)

Bob
PS. If you MUST autocross on them, put a lot of air in them to minimize contact patch. A small but hot contact patch will handle better than a wide but cold contact patch. I'd start at 25psi and go up until you get heat/grip. 2-drivers would be better on that tire for the same reason.

[Marc Lisner]

I have been autocross on dunlop DBS tires for about 1 1/2 years and I have thought that they were a wonderful tire and heat up well/sticky. i have been running 9 up front and 10 in the rears.

I am getting my first set of truely soft tires monday and getting rid of my old 100+ runs DBS tires, and going with Vega whites which I think will work best for me. Am i in for a big change in performance in grip, I'm hoping for atleast a second more with the vega whites.
I didnt realize that there were so much better tires out there back when I got them.

[Alan Sheidler]

Dan,

You did not say what class the kart was running in. If the inquiry is regarding the FJ classes, that is an appropriate tire!

Depending on the surface and temperature, we also run between 10 and 12 (occasionally 13) pounds in my sons's Gold Kart Dunlop DBS's.

Alan

[Daniel Morency]

Although we do use the SCCA rules as a guideline we don't use their tire requirements or their weight limits (we don't have scales to check... )

www.cumberlandmotorclub.com

My wife and I run in an adult class running the KT100 and a 4 hole can...

I picked up my kart with 2 KT100's and my son (14) talked me into letting him run one, when he got almost 50 MPH in the driveway I figured I'd run the can for a while too. I have pipes for all 3 of the KT's that I have now and I have a 100CC PRD that has a pipe too.

The 100's with a pipe would run vs the 125's and not be competitive so I'm sticking with the cans for now...

We run pretty fast vs the cars with the cans, I'd have several FTD's if I didn't bring a friends 120CC Sodi kart that he rents.... (He owns a local indoor karting establishment) $25.00 for a day's runs in a 24.5 HP kart.... sweet! I love the smell of the 50% synthetic 50% castor that I'm running and the kart just screams. My daughter runs a Briggs raptor engined kart with a plate... She's 9

Thanks

Dan