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Discussion Starter · #1 ·
I went from stock rims and toyo RA1's to 18x11 with 295/30 and 18x12 315/30 Pilot Sport Cup Tires.
I discovered right rear rim was slightly bent also and the shop he must have had it done at didn't tell him and just dumped a ton of wheel weights near it.
Car felt horrible all day, oversteer easily not good under braking,etc.. Couldn't get on throttle at normal spots.
Track Times: 3 seconds slower consistantly.

That's right, I know this track timed it. Blew my mind also but it felt alot slower.


I run 1.5 camber in front and 1.25 in rear. 1/8 out in front and 1/8 in rear on toe.

Took tire temps: (all below 150 which seems way low)
Taken straight off hot track on pit road.
Front's went from 117-123 outside to 135 inside.
Rear (on bent rim) 147 O/M/and inside
Other side rear 120 outside to 140 inside and middle

Now is it me or does the tire temps seem weird given lack of camber.

Are tires shot???

Is bent rims causing everything else to go weird??

Just really bumped when you make investment and car goes several seconds slower.

Any thoughts would be great.
:yeadog:
 

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Discussion Starter · #3 ·
Got them with the rims. He brought them 3 years ago and my guess is they were old then based on other experience with tirerack with these tires.

Don't know how to tell build date on tires?
 

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On the inside sidewall there should be a 4 digit date code: 3602 = 36th week of year 02. Properly stored, the date isn't as important as the number of heat cycles.

Sounds like you didn't have much confidence in how the car was handling and that would easily account for rise in lap times. You have a lot of rubber under the car now and will have to drive harder to put heat in them. Maybe too much pressure and they are not rolling over enough to heat the outside.

Check rear toe and make sure it isn't out. That will make the car unstable under braking and the car will seem to oversteer.
 

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Heat cycles are the key, but any tire that's 3 years old...I'd say that was a major problem!!!! Tires do have a shelf life (for maximum grip) and when they get that old, you could be suffering from dry rot among several other factors. Plus the fact, 3 year old tire technology is just not going to be as good as the newer stuff. Tire companies change their compound frequently so those could have been rock hard right from the start.

Unless the rim was severly bent causing the tire to lose air, that probably wasn't a major factor - but I'd still take the rim back to the guy and have him either fix it or pay for it.

Definitely get some new tires though.
 

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Discussion Starter · #6 ·
I was running it really hard and was running recommended pressures of 34-36psi. Toe and camber were right on where they normally work fine.
Ran my Toyo's back on on the weekend and man they felt grade compared to the PSC's.

Rim wasn't bent enough to lose any pressure but was interesting that was max temp (although at CMP you would expect that to some extent with the left rear tire).

Will check date.

My sweat is now do I get replacement PSC's after totally being let down or go with Toyo's but knowing I have to fit a smaller tire on front (275/35/18) like world challenge cars.

Almost need to get a tire trailer and just run big hoosiers all around.
 

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Discussion Starter · #7 ·
OK build dates are weird.

For front tires (295/30/18's) it says in the dot circle 0302
So I guess pretty damn old.

The rear tires (315/30/18's) have it in different place just at the end of 11 seguence number last 4 digits are 3003
So I guess 30th week of 03

Well 2-3 year old tires that have been sitting and not loved might explain my issues.

Would they lose 3 seconds minimum though??
 

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I just checked my used Kumhos. One heat cycle before I got them this spring. Date code 0203. I was 3rd overall in field of 140 cars at Autobahn timetrials event. Tires felt fine.

If you call Michelin they will tell you date code does not affect tires if they are stored away from heat and ozone. My friend bought odd size MPC tires from Tire Rack and date code was from 2-3 years earlier. He thought it was BS, but they worked fine.

3 seconds?... they would have to be as hard as a rock
 

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Discussion Starter · #9 ·
Yeah it was ridiculous.
Talked with one of the guys from Viper days as I may do there VIR event.
He said they were likely shot as if the guy does a few heat cycles and then they sit for several years not well stored they go to hell.
He didn't seem shocked when I told him how bad times got.
:eek:
 

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3 seconds seems a lot, but with tires that old, anything is possible. Also, 3 seconds off what time - what time of year...and what conditions? Was it 3 seconds off what you did the same day with different tires???

Depending on what time of year you went, it's not unusual to drop 2 seconds just from heat and deteriorating track conditions (Roebling and Moroso come to mind). If you had old, hard tires on top of that, 3 seconds off is very possible.
 

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Discussion Starter · #11 ·
Was at CMP.

Running 1:51-1:52 during morning times and 1:53's in afternoon at May 1st NASA VA event.

Ran 1:56's and could do no better on the PSC June 10th.

Slightly warmer but not much.
 

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The difference at CMP between May and June could easily be worth 2 seconds. That track is ultra slick to begin with and when you add in the additional heat, you'll be dirt tracking quickly. Having said that, it's probably a combination of things...old tires, the track difference between months, and proper set up of these new tires. It didn't look like your temps were off, but that's just one factor. I also don't know what else you changed on the car...other than tires and wheels.

Since you went from stock rims (17F and 18R) to 18s all around and put 11" wide rims on front with 295s up there and just 315s in back, you now essentially changed the rake of the car and raised the front end...plus you put more cornering ability on the front which would explain you being loose. CMP is a pure traction track - the more you have coming off those slow corners, the better your lap times. If you can't put the power down or the car is severly loose, your lap times will suck.

You changed so many things (including the time of year) that it's nearly impossible to judge. First thing though - get fresh rubber. My old crew chief said: "Never chase bad tires." In other words, if you don't have fresh rubber on there, don't try to constantly monkey around with the car settings...you're wasting your time.
 

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Discussion Starter · #13 ·
Great advice. I agree.

Bummer is I don't want to invest in these tires at the prices they cost if they won't be quicker.

The rake shouldn't change at all because the height difference front to rear is the same as the stock difference (.5).

Only changed tires and rims all else stayed the same.

I might just fix rim and get a tire trailer and start just towing the rims with some good cheap goodyear slicks on them for $600 all around and abuse those instead.
:-?
 

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Silver sounds like you may have gotten a old set, but I have found that the PSCs are not as effected by heat cycles as other brands. I know that to get the most out of them the tire temp has to be up to 160+ and don't go off until about 180+. I do know that I ran closer to a turn and 1/4 toe in off 0 on both sides rear for auto-x. That and I also found that they worked better with less (not much) camber, esp the rear. Also with two more clicks of compression on my JRZ, from what I used with Hoosiers.

My one real track comparison was a day at Sears Point (temps in the low 60s) Comparing a GT3 with PSCs and My car and a GYF1 equip 04 Z. I almost got the tire temps up to 150s, same for the GT3.

But they are costly. but will out last the $600 set of GY slicks 3 to 1. but go with what you are comfortable with.
 
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