ZR1 Tires

[Charles A.]

This might be one dumb question but have to ask. Have an original set of 90 ZR1 tires with 1100 miles. Only problem car sat for 7 years. Naturally very flat spotted. Anyway to make them round enough to drive for judging? Plan on replacing after judging.Also,what is the best current new tire to buy for performance and least deduction come judging time?

[Duke W.]

Re: ZR1 Tires

Whether or not they are reasonably safe to use depends on how they lived.

Did they go flat with the car's weight on them?

How much exposure did they have to UV light or ozone?

If air was kept in them the flat spots may round out with a few heat cycles.

Duke

[Charles A.]

Re: ZR1 Tires

They were in a dark garage. Air pressure gradually went down to 5 lbs aprox. and sat there with vehicle weight.

[Wayne K.]

Re: ZR1 Tires

Chuck,

I would inflate them to 45-50 lbs. and let it sit for a week. Then let them down to 35 lbs. and drive it warming them up slowly. As Duke has mentioned, running them through a few heat cycles may round them out

Wayne

[Duke W.]

Re: ZR1 Tires

The dark garage was good, but allowing the tires to drop that low for an extended period of time could damage the sidewalls.

Pump them up to normal pressure and give the sidewalls a careful inspection. If there is severe cracking or distortion of the sidewall, they should not be driven at high speed, but do some driving on surface streets to give them a chance to "straighten out".

Some think that tires should be replaced arbitrarily after so many years, but there is no way to come up with a number. There are too many variables beginning with tire construction and materials. Then there is the life that a tire leads.

If you start with a high quality tire (and you can use speed rating as a quality surrogate. The higher the speed rating, the higher the construction and material quality), and it spends most of it's life in a dark garage, there's no reason to arbitrarily replace them at any point in time, but as they get older, they should be inspected frequently for signs of trouble.

Duke

[Charles A.]

Re: ZR1 Tires

Thanks Duke and Wayne will let you know how it works out.

[Ken A.]

Re: ZR1 Tires

I wouldn't trust those tires for anything other than rolling the car on and off a trailer. The ZR-1 is a 180mph car. Driving with those tires is like playing Russian Roulet. By the time my wife's 88 was 12-13years old, the tires were hard, and it stayed in a garage all the time except for the 1000 miles or so year that we drove it. The tires would break loose just driving out of a driveway. It scared me to think what would happen on a winding road, so we replaced them. Of course we were docked points when it was judged, but that didn't keep it from getting the McLellan and Crossed Flags awards. And, we can still drive it. If you want to keep them for judging, OK, but don't drive it with those tires. Just had a friend pretty well destroy his 40 Ford when a 10 year old tire seperated on the freeway. Only straight sheet metal left was the roof.

Ken

[Charles A.]

Re: ZR1 Tires

Thanks Ken. Do not have my judging book yet but is there a current production tire that would be safe and allow the least deduction.

[Patrick H.]

Re: ZR1 Tires

Chuck,

If it were me, I'd buy a set of additional ZR-1 sized rims, and mount new tires on them. Those will be your driving set and you won't need to worry if they're original, chrome or custom aftermarket.

Then keep your original set of wheels and tires for judging. I do this with my 72 and it works well.

Patrick

[Duke W.]

Re: ZR1 Tires

My '91 MR2 has the original front Bridestone RE71s and they work just fine. They sat in my tire rack for nearly ten years while I ran DOT legal racing tires on another set of OE wheels.

It all comes down to individual cases, and the quality of the tire is a BIG determining factor. I would be willing to bet any sum that your buddy's '40 Ford had a cheap set of tires without the nylon cap belt that H and above rated tires have.

That's why I always recommend buying the highest speed rated tire you can find in the appropriate size regardless of how fast you plan on driving. The higher the speed rating, the safer the tire, and tires with nylon cap belts rarely experience catastrophic tread separation and disintegration, but cheap tires suffer this fate more often than most probably know.

The ZR-1 tires are Z-rated - very high material and construction quality. If they were cheap tires without a nylon cap belt, I would say replace them. Of course I would say replace them even if they were brand new.

Don't put cheap non-nylon cap belted tires on ANY car you own, and high speed rated tires will last many, many years on a collector car that is garaged and driven infrequently.

Duke

[Charles A.]

Re: ZR1 Tires

Thought of that Patrick but the 35 and 40 series wheels are a bit much for the wallet. I do the same as you with my 67. Anyway thanks for the thought. Think I will just buy a new set of Goodyears put them on correct wheels drive to the show and still ahead of the game with driving points.

[Patrick H.]

Re: ZR1 Tires

The wheels are too much for your wallet? I think you mean the tires. The wheels are not that expensive - much less than the tires. And, if you're buying new tires anyway why not the wheels???

I'd watch zr1netregistry.com as well as zr1.net for a set of low mileage take-offs. I see a set of 4 wheels for $650 on there right now.

Patrick