Hey all,

I know the tire pressures topic has been beaten to death, but I haven't found a discussion specific to my application: I have a MC w/the base suspension (non SS+) and I'm running Kumho Victoracers on a set of 7-hole alloys (5.5" wide).

Basically, I can't get these tires figured-out. I ran all last season using just Continental all-seasons and that was great: Since the car was my daily driver, I had a good idea of its transitional responses on that set of tires, and I could get it to rotate pretty easily.

The Victos make it into a different car: There's much more grip there, but I don't have an intuitive feel for what the car's going to do.

Basically, I'm trying to get a baseline for pressures and pressure managment during runs.

1) What's a good starting pressure for this setup? I've tried everything from 55f/50r (feels good, but not too much grip), down to 45f/35r (seems like some tire squirm here, but more grip). I've heard that b/c the MINI is camber-challenged, you need to run higher-than-optimum pressures up front to keep from cording the edges too quickly. Is this true?

2) As your tires heat-up during your runs, should you let-out air to return them to the original (cold) pressure, or just let them go?

3) What's the rule of thumb for adusting handling w/tire pressures? From what I've read in other topics, to increase rotation you lower rear pressure while keeping the front the same. Correct? So, I could start out at 45f/40r and adjust up for less rotation and down for more?

Also, could someone point me at a link for chalking tires and making adjustments based upon the chalk?

 

I'm using the same setup with a MCS in SM class.

From-
http://www.tirerack.com/tires/Spec.j...ictoRacer+V700
The max tire inflation is 44 psi so I don't think I would try running them at 55 and 50 psi.

Every car is different due to the suspension, weight, your track, the temp of the day.
You might try 40-42 front and 34-38 rear.
Read-
https://www.northamericanmotoring.co...ic=25554&6

I have lowered springs, rear swaybar, adjustable control arms, and strut tower brace and usually run 39 front and 42 rear with yokohama ES100 in 215/45-17 but now I will switch to the Victoracers now.

Tires do heat up but they will cool down between runs. You won't be able to tell too much unless you have a tire pyrometer. But the higher heat will push the psi up. Most times there is plenty of time between runs for my tires to cool off. Then you have to decide how much to adjust.

Tirerack.com mentions-
"The V700 will work well on most cars with inflation pressures between 35 and 40 psi ("cold" inflation pressures for autocross use and "hot" inflation pressures for racing use). Cars that are light, well balanced and relatively easy on tires will find slightly lower pressures may work for them, while heavy, high horsepower cars that are generally harder on tires may find that they need slightly higher inflation pressures.

Generally adding air pressure in small increments (2 psi) to the tires on the end of the car that looses traction first works best. For example, if a car is understeering, add pressure to the front tires. If the car is oversteering, add pressure to the rear tires."

For lots of tire info see
http://www.tirerack.com/about/techcenter.html

For psi suggestions see
http://www.tirerack.com/tires/tirete...n/racepres.jsp
http://www.tirerack.com/tires/tirete...k_pressure.jsp

For Victoracer care see
http://www.tirerack.com/tires/tirete..._v700_care.jsp



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Aloha Hawaii

 

I have run tires over the "max pressure" listed on the tire for years.... it is common practice in the autocross world..... I know of people who have run R tires in the 60 pound range!!!!! but I don't think any tire setup on a MINI needs that much... but 50 to 55 is a range alot of MINI drivers use...

 

I've only had a couple of events with what I would call "representative conditions;" our first two events were run at 35 and 36 degrees F, respectively. Those were like driving on ice, as the Victos had no chance to heat up. Never done a 540 spin in a MINI, but I did that day!

Anyway, I had one good event on the Victos (won the class by 3 seconds) but that was against mostly novices on street tires, so I don't think that counts.

Last event was just awful...I was a whole second behind the other guy w/Victos (an 01 Civic).

Basically, I've been chasing a baseline setup all season, and wanted to know what others are running.

 

I haven't met a whole lot of people running victoracers. I'm running v700's 205/45 16's but this should work for you. Not having access to a pyrometer what I did was put chalk on the tire right where the tread meets the sidewall. I started with a baseline of 45 psi F/R and adjusted the pressure up or down until the chalk came off right to the edge of the tread. Raising the pressure will move the contact point up on the tire. The front is the most critical because the tires will get torn up if the pressure is too low. I ended up with 50 F/ 45 R but you might end up lower than this because I believe your sidewalls may be a bit stiffer then the v700's.

 

minihune -- did you just recently by holeys and v700s? i don't remember seeing them on your car when you ran your 2nd race. or maybe by vision is failing me.

>>I'm using the same setup with a MCS in SM class.
>>


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All,

Thanks for the wonderful responses. After alot of trial and error, plus an Evolution school, I've finally settled on 42f/36r as my pressures, with adjustments from there.

I've found the best technique is using good old shoe polish at 3 points around the tire; that guided me right to the pressures as above.

Also: Yes, the Victo and the V700 seem to behave very differently: A guy at our Evo school had his V700's chunk very badly at the front, and he was running 50/45. Overall, I'm very happy with my Victos so far this year.

 

the v700's will chunk if you run them unshaved and they get too hot. The victoracers take longer to warm up but are a more durable tire.