Tire info

[Q45tech]

Copied this from different forum where I post might be of interest

http://www.cb-racing.com/PilotCup_Presentation.PPT

Typical race tires will be 25-35 Shore A hardness while typical oem highway tires will be harder at 55-75 Shore A. http://www.instron.com/hardness/shore/index.asp

http://www.silentroads.nl/down...2.pdf

[SmithSR]

Where can one purchase a Shore durometer locally? Ebay only?

[Q45tech]

This is the one many tire engineers use in the field at the tracks:http://www.ccsi-inc.com/new/p-rex-2100.pdf

$355http://durometer.com/dealerus.htm#maphttp://www.durometer.com/models.php

[Q45tech]

Most interesting is that new tires increase their hardness by roughly 1.0 Shore A units per 1,000 road miles. Obviously the exact amount varies with tire temperature exposure, but 10-12 units increase in a year of use [12,000 miles] is in the ballpark.

Why I believe most tires are seriously compromised after 20,000 miles.

Tire manufacturers USE this phenomenon to make long wearing tires..............the wear rate for each 10,000 miles gets less and less......if you blend the tread compound corrrectly.

Long wearing tires get hard really quickly, sometimes in just 3-4 months of Summer use.

[Q45tech]

"When taking durometer reading the tire should be mounted on the rim with the proper air pressure. This supports the tread to make your durometer reading more accurate. Remember a durometer is a pressure sensitive device. If the tire tread face is compliant when you attempt to use the durometer the readings are not accurate. Speaking of accuracy, two people could use the same durometer on a tire and get different readings based on how much pressure they applied to the durometer.

When using a durometer on Autocross compounds you would normally see a higher initial reading with the durometer reading dropping "settling". EX: the initial durometer reading is 60 but the needle drops until it stabilizes at 54. This characteristic is rebound, This type of reading indicates low rebound characteristics.

Using a durometer on a tire at room temperature is less than desirable. Ideally you want to test the durometer of your tire at the temperature the tire is going to see at the track. Manufacturers use compound heat curves to help them predict how a compound reacts during competition. Manufactures use really cool scientific instruments but you can check the heat curve of your tire at home. To chart a heat curve you need the following: pyrometer, durometer, heat lamp, paper, pencil. Take a durometer reading at room temp, record the temperature and durometer reading. Heat a spot on the tire with the heat lamp, while keeping tract of temperature readings using the pyrometer. Take durometer reading every 20 degrees. If it's an autocross tire chart the durometer reading from 100 to 180 degrees, road race tires 140 to 220 degrees. I would expect the durometer readings of autocross tires to soften at 100-110 degrees and stay consistent to 160 to 180 degrees. Road race compound tires the durometer reading should be consistent from 140 to 220 degrees.

An autocrosser wouldn't want a tire which didn't soften until 140 degrees, this tire would be almost useless the first couple of runs (unless the air temperature was hot). Charting heat curves are most useful when comparing different compounds or brands of tires. "

[Q45tech]

A 1992 Q came in with 4 different brand tires, that might have been ok, but the rear were 205/65/15 and the fronts were 215/65/15.All were worn almost to the cords. It snowed the next day.

[SmithSR]

A 1992 Q came in with 4 different brand tires, that might have been ok, but the rear were 205/65/15 and the fronts were 215/65/15.All were worn almost to the cords. It snowed the next day.

An employee's mother's Q came in with 16" 'T' rated 700wear rating Toyo brand tires. This particular tire is advertised to last 100,000 miles.

Front inside shoulders were worn to cords, rears were excessively worn in a similar pattern, but not quite as bad.

Alignment documented from dealer since car was new...tires rotated on scheduled maintenance intervals... air pressure maintained at 40/38 .... all according to her records.

Tires had 16K miles on them, and were ruined. The employee brought the car in <when> it was snowing!

[Q45tech]

Tires are tested in the lab with ZERO camber. If a decently soft tire [something like the oem 170 tread wear index] last 20,000 miles on a Q I jump for joy.

I am happy to get just under 30,000 miles on the Pilot H4 [in the extra load 235/60/15 size] even though its 400 indexed and advertises 40,000 miles.

[Q45tech]

Keep reminding members to never let an old Q get too close to your rear bumper................based on my observations of the condition of the majority on the road at least in the Atlanta area.

[maxnix]

Hmmm...I'll remember that when I follow my wife home!

Oh, wait, my damn AVS dB still have too much tread! Guess I will wait until the fall to replace.

SmithSR, want to split the cost of a durometer? Maybe then I can justify a new set of SZ50 EP. :ylsuper

Great information as always. Real world data surely beats armchair speculation. Nice to be back in Kansas again instead of OZ or the fashion runway. Thanks, Q45tech!

[96QQ45]

I went about 40,000 miles on my Yokohama YK420's from discount tire. The last time I had a rotation the car pulled like crazy to the left. I had the alignment checked and it was fine. I went back to discount to have them checked out and they gave me two under warranty! Thanks very much. A short time later I looked at the other two and the insides were eaten up so had to buy two more-no warranty this time-this guy new my Q ate the tires. Recently I had to have the upper links replaced so I figure that contributed to the wear pattern. I know the alignment was good all along but still I'm surprised I got that many miles on them. The tread was still good all around except the inside edges were toast.

[szh]

In the presentation, I thought that this was a very important point:

Quote »Well, if you are confronted with the choice of squeezing a big tire onto its minimum recommended wheel width or stretching a smaller tire onto a relatively wide rim, you might want to pause for thought

We have found the smaller-tire + wide-rim combination, with its accompanying “high-tension” inflated shape, can be more efficient:

• More direct yaw responseDecreased “phase lag” between steering wheel input and vehicle turn-in
• Less “overshoot” at corner exitLess of a tendency to “wiggle” at corner exit (thus upsetting the car) when you roll back into the throttle
• Can result in decreased negative camber requirementsthus increasing braking and accelerating efficiency
• Can improve vehicle response to air pressure tuning

[/quote]I think we all have a tendency to want to get the widest tire we can to fit on the rims we have, and this is not always the right answer, I guess!

Z

[Q45tech]

Good tire tread depth is not the same as having good tires.

In fact tread and tread depth are the antithesis of handling in dry or damp conditions. The voids do nothing in dry conditions except reduce the amount of rubber on the [interlocking with] the road.

Takes a superior tire to survive the Q front service with all the caster and camber gain in city turns.