98 ITR

Hey guys,

Tail end of last summer, we noticed that there were small cracks all over the tread grooves of this set of Kumho SPT tires. The sidewalls do not seem to be cracking, only in the tread grooves. Never seen anything like it. The tires are a few years old, are stored indoors, and only driven in the summer. Car is properly aligned with no abnormal wearing. Tire pressure is kept at OEM specifications. Car is only used for daily driving.

All the tires are like this:


There is about 40% tread left on the tires, but we're wondering if this is cause for concern? Go ahead and run them for the summer, or replace them immediately?

Thanks!

TunerN00b

When were the tires made? It's on the inside sidewall.

How were they stored? Were they cleaned properly and stored in airtight bags?

They simply look old and hard, but without answers to those question we can only guess if they're ok to drive on or not.

Kumho Tire

Thanks for purchasing Kumho's! And thanks for the photo! From the appearance of the cracks in the photo it loooks like superficial cracking due to the rubber beginning to age. This is common for tires as they age. We put stuff in the rubber to leech out to keep the rubber pliable as the tire ages. As the agents we put in decline in the rubber, the rubber begins to become less pliable.
The small grooves in the shoulder are one of the first places cracks will appear due to the stiffness differences between the groove and the stiffer tread block.
The photo shows some evidence of spirited driving which increases the movement of the tread blocks. This can quicken the development of the cracking in the shoulder grooves.
The earlier questions would better define the cracking, how old are the tires? How were they stored? How much heat and sunlight have they been exposed to? The Answers to these questions would provide more info and insight into how long the tires will last.

Rick

98 ITR

Hi Rick,

Thanks very much for the reply. Tires are a few seasons old, but in order to get the exact number for you, I'll have to pull them out of storage again (we had a spell of nice weather, then it snowed again so back they went). Is there a code or something on the inner sidewall that has the manufacturer date included?

As for sunlight exposure and storage, as stated, the tires are on their third summer season and might have approximately 15,000kms on them (around 10,000 Miles). The car was parked in a garage for the first summer season, then outside for the remaining two. There is a gravel road that the car travels on at least once a day, so that might be something to consider (although the car never sees anything more than 20kms/h on gravel). Tires are stored indoors in a dry storage garage. Tires are either stacked on top of each other, or placed on the ground, upright in a row. We do not put them in bags. Tires are cleaned before storage. Once in a while we may use some Armor-All to clean them after a wash.

With specific regards to heat, the tires are on a daily driven 06 Honda Accord V6 MT. Other than the odd off ramp, or country road, the car is driven conservatively. These tires have never seen the track, and have seen no serious "heat cycles".

From a safety standpoint, do you see any reason to replace the tires now, or should they be safe to drive on?

Thanks again,

Ryan

TunerN00b

Even though you ignored my reply, here's the answer to that question:
http://www.tirerack.com/tires/tirete....jsp?techid=11

98 ITR

My apologies. Rick was echoing your questions so I addressed them in one post. Didn't mean to seem ignorant.

Thanks for the link.

TunerN00b

No worries.

If they're under 6 years since manufacture, I'd probably use them. If they're older than that, I'd just throw them out since they weren't stored properly. But, that's me.

98 ITR

Thanks again guys.

Manufacturer date on the tires is Week 46, 2005.

Also, for future sets, what would be the optimal way to store the tires/rims during the winter? Been storing tires like this for years with zero problems until now. Just curious ...

TunerN00b

In an airtight bag, away from sunlight and moisture. Clean tires with water before storing, dry completely, and don't put a coating on them (armor all, etc...).