Hi everyone,
What do you recommend I do with MG Reds on a grippy track when it comes to LO206.
Also, what PSI don you recommend for wets.
Very very generically, 11-15 psi for Reds on a grippy track.
Wets can be anywhere from 15psi if it’s almost dry to 30psi if it’s a downpour
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Agree with Derek’s range on the pressures.
15 for cold track with low grip, 11 for hot track. It’s a tuning tool, so you’ll have to assess after each session whether you need to make an adjustment.
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Not to highjack this thread: is there a way to measure how much life is left in these tires?
I have MG Reds that are getting quite old, they have 9 rounds on them and two tests (about 60 laps). Some people at my local track say they last all season, some seem to spend money on new tires more often. The last time I went out I had no grip at all and was unable to match times that I did at the same track in similar conditions. I am going to assume the tires are gone, but there are so many other factors to consider…
It was very hot when I last raced these tires (above 90 degrees) and after asking around I ran very low pressures (9 psi cold). Perhaps I was running too low of pressure and they were not actually getting up to temp? I’m still new and learning about tire pressures, so generally just ask what others are running and make minor adjustments to see if I can learn about how they affect the tires.
Is there also a pressure change I should be making to compensate for older more worn tires?
Reds will heat-cycle and slow down far before the tire gets to the wear markers. Usually there is a lot of meat left on them and they are just heat-cycled out and the pace drops off over time. 9 rounds is a lot.
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TJ is spot on. When you’re noticing what you’re noticing, it’s time.
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Thanks, yeah I think they are toast. I really wanted to learn as much as possible before getting new ones. Now that I have some experience and lap fairly consistently I think it is time to get new rubber and start planning for more regular tire changes.
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What is it that kills the tires? Does the durometer change over a series of heat cycles?
Yes. As the rubber heats up and then cools down, it hardens. UV and aging can also harden the tire.
I might need to get a durometer gage or whatever it’s called.
When I was looking at ovrp club lo206, they allow only two sets of tires a year over 14 or so races.
How do you know when it’s time to dump hard tires? Assuming they don’t wear down like our softer tires would (and when it’s time to throw them out is obvious). They get too coned? Start feeling off?
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Stopwatch!
I have an LO206 Cadet running MG Reds, and there it seems to me that we definitely see a couple of tenths after 6-8 heat cycles (so 2 race Sundays for us if we don’t run the practice session on race tires) and then kind of stabilizes for a bit. By the time get to ~15 heat cycles we see them fall off by .5s+. It happens a little faster in middle of summer vs. spring/fall.
My driver - not an expert by any means - doesn’t feel the couple of tenths drop-off. He definitely feels it when it starts getting to .5s+, comes off the track and says “it just doesn’t have any grip”.
We have run a practice set of MG Reds until they corded. Once they got to about a second per lap off a new tire, they stayed there until there simply wasn’t any rubber left on the tire.
We do all sorts of things that are probably worthless to try to preserve tire life. I wrap them in saran wrap and take all the air out at end of race day. We rotate them around and ignore the directional arrows to try to avoid a single tire staying on the highest load corner of kart all the time (RR for us). I take them in the house and store them in the basement between races instead of leaving in hot trailer. Again, not sure any of this helps at all but it makes me feel like I’m at least trying! 
If a club’s tire limit doesn’t apply to practice days/sessions, well worth having a practice set of tires to keep heat cycles off your race tires. The biggest downside to that is if the condition of the practice tires differs too greatly from the race tires, chasing your chassis setup to optimize times on the older tires can take you away from where you need to be on the newer/grippier tires.
When they go slower and feel like they are losing grip, then you know it’s time to swap them out.
At Dousman for example, the right rear gets burned off quicker than the rest, so you can really feel once the tires start to drop off when you go through turn 1, the quick almost flat-out 90° left-hander. The kart just wants to float up the track at apex.
From what I understand the degradation also comes from the release of oils with from the tire each heat cycle. Over time the oils dissipate and the characteristics of the tire change.
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I have a durometer but not really sure what to do with the ratings. They seem to change from other factors such as whether a tire sat in the sun for a few minutes before taking the reading.
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Yes, durometers are tough to get an accurate reading on. You need to be consistent in temp, timing, conditions, pressures, etc. it’s easier to just watch the stopwatch and keep good notes of run time on them. After a few sets, you will get into a groove and figure out a rotation/schedule that works for you.
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We run the MG reds about 3 race weeks, where every weekend is 15 sessions with 3-8 laps each session. The issue I am seeing is that older tires take 4-5 laps to get to good lap times. Others seem to switch tires after 1-2 weekends, which I do not like because you are partially buying yourself a good race result.