[cawayne]

I'm running shaved Toyo RA-1's at the track and they are close to being slicks. They are still gripping like crazy and I feel total control going through corners. At what point do I need to replace them before they become dangerous? Is there something to see or is it more on how they feel? I rotate the tires so the least treaded is on the inside rear depending on the track direction. I get inside rear tire lift but that's another story

[Vypurr]

A tire is considered no longer usable when the tread depth is at 2/32nds of an inch or less. Tires have tread wear indicator bars within the tread channels that are 2/32nds of an inch high. If these indicators are flush with the surface of the tire, then your tire is legally bald.

If you can't find these tread bar indicators, you can use the penny test. Insert a penny into the tread of the tire with Lincoln's head facing down. If you can see the top of his head, then your tires need replacing. However, you may experience a loss of traction well before the tire is completely worn out.

Rowleys Tires & Automotive Services - Frequent questions

[Flycaster]

No traditional tread indicators on racing rubber, but usually your lap times will fall off signifcantly, due to multiple heat cycles, before the tire gets to be "dangerous" for most amateur drivers. How racing miles and heat cycles do you have on them? Do they get greasy after just 6-8 hard laps?

[cawayne]

It's difficult to say how many track miles I have on them. I probably have ten track days, averaging six thirty minute sessions on each track day. They don't feel greasy, I don't feel like I'm any slower but can't officially tell as they are not timed events.

[stretch]

RA-1's are good well beyond the point of no tread showing. They don't deteriorate from heat cycles the way other tires do, either. They'll just continue to get faster.

[Flycaster]

Originally Posted by stretch

RA-1's ...don't deteriorate from heat cycles the way other tires do, either...they'll just continue to get faster.

All soft compound competiton rubber is affected by multiple heat cycles; I've seen the impact many times with a durometer. I also have trouble believing that they are faster at lap 60 than they were at lap 10. They're nice dot-legal rubber, but they're not "wunder-tires."

There are bunch of guys who use them in the regional SCCA/Vintage race series (all types of cars, some extraordinarily fast, some not). I spoke with one of them last night (corvette owner) and he tells me he goes thru 2 sets every 4 events before his lap times fall off (1 second plus) and he replaces them - if my math's right, that's about 140-150 miles per set, 3/4 of which is at full race speeds. Frankly, that's pretty damn good, but there are other guys (with unlimited funds) who go thru a set or more every weekend. But, I'll be the first to say these guys are driving a LOT harder and faster than just about anyone on this board, with the exception of guys like mxpop. Maybe he can chime in with his experience, but I'm not sure he uses this rubber.

Regardless, if they still have decent grip all the way thru each session, run them - just be aware that they "go away" slowly so you may already be several seconds slower without even realizing it. If your track rents transponders, use one; if not, get someone to stopwatch you. It's the only way to know.

[cawayne]

Thanks for the input.

[RenoSTi]

Originally Posted by Vypurr

A tire is considered no longer usable when the tread depth is at 2/32nds of a inch high. If these indicators are flush with the surface of the tire, then your tire is legally bald.

If you can't find these tread bar indicators, you can use the penny test. Insert a penny into the tread of the tire with Lincoln's head facing down. If you can see the top of his head, then your tires need replacing. However, you may experience a loss of traction well before the tire is completely worn out.

I have read that the new test recommends using a quarter (instead of a penny) which is equivalent to 3/32nds of an inch. With the wider tires in use on most cars now, the experts feel the extra depth is needed for safety.

[kenji815]

get a tread measure gauge at yoru local auto parts store.
2/32nd of a inch would be good indication you need new tires.

[Matt Drown]

Originally Posted by kenji815

get a tread measure gauge at yoru local auto parts store.
2/32nd of a inch would be good indication you need new tires.

Amazon.com: Tire Tread Depth Gauge: Home Improvement

Or pepboys for $5....

[cawayne]

Some of you guys at the end are not reading my original message, these are shaved tires for use on the track. I'm not worried about them being street legal, they are track tires only. I just want to know how far I can take them safely with next to no tread. Do wires start sticking out or do they get too greasy. From earlier responses I now know that they get better with age like good wine, just monitor my times as well as how they feel grip wise to get an idea of their life expectancy. I appreciate you providing tips on street legal tires but that wasn't my question. Thanks anyway.

[T3h_Clap]

there should be depth indicators eventhough they are near slicks.

usually little dimples in the tire.

when you see cords your tire is beyond shot.

the goal obviously for you is to complete a full day without having to stop b/c your tires are dead.

It sounds like you've gotten alot of good life out of these so far, I'd at least start preparing to buy a new set.

I don't personally have any RA1 experience, but I'll talk to my friend who has used them and see if he's got any ideas to judge tread depth when they are near slick.