I have my 1974 corvette shod with cooper cobra's 2.25/60r15's. I have has tread separations on two of the tires. I'm not into criticizing the tires, because at the time of both incidences I was driving 75-85 mph on a hot day and may have caused the tires early demise by not having tires of correct speed ratings. [unsure of the cooper cobras speed rating.] My question is what speed rated tire options do I have in this tire size category? Most I see listed get kinda of vague or have seriously low speed ratings. Are there any tires out there in this size that are safe on a hot day [90 degree temps] at speeds in the 75-85 mph ranges for my vette? I'm really not interested in changing to 16 or 17 inch rims so I would like to know only about 15's. I know there are some people on this forum who could help me with this problem without all the tire salesman hype I've been getting locally. Btw I made 18.7 mpg driving this speed. It was amazing to me as the combination in the motor and trans is this, Bone stock 350 with weiand 8004, 650 edlebrock carb hei ignition block hugger headers chambered exhaust and th400 trans. I figured the th 400 would not do this well, so Iam pleased.

 

The only v-rated tires that I know of in 15" -

Firestone Firehawk PV41
Goodyear Eagle RS-A
Pirelli Scorpion Zero

 

There is little or no choices for performance tires for the C3 if using 15" wheels. The Goodyear and Firestone above is V rated but only if your willing to use the skinny 225/70/15. The Perelli is designed as a truck tire.
If you go with the 255/60/15, you are more than likely going to find H rated tires, 112 mph.

 

The 'LOW' speed rating on modern tires is an 'S' rating. You can find it on the tire somewhere, normally with the load rating. The size of 225/75r15 will be followed with an alphanumeric figure like 89S. the 89 or whatever that two digit number is, would be the load rating and the S or H would be the speed rating.

There is NO SPEED RATING that is so low, that a tire would blow at 75MPH. The coopers were either defective or they were old, or something. Tires only last 4 to 5 years before becoming unsafe to drive on.

 

FYI, H rated tires are good until 130 mph.

trw
I'm running Falken Ziex 512 or 502 H rated at 215/65/15. I like the handling. I feel I'm more limited by my suspension (very old) then the tires.

 

One of these days some tire manufacture will wake up and make a speed rated (at least a H rating-130mph and in a P245/255 size) tire for us 15X8" wheel owners. There has to be a huge market out there for such a rated tire when you consider all the C3 Corvettes as well as all the 15" shod musclecars that were made. While I don't do 130 mph for extended periods, I would pay for the peace of mind.

 

Speed ratings are conservative...not exact.

 

The tread separation described (2 tires) tells me they may have been underinflated...if,you are going to run sustained speeds of 80mph..you must adjust pressure accordingly..
Underinflation causes tires to heat up ...

 

I run Yokohamas 255x60, only ones I could buy in Australia, only 130mph rating but Im happy with them.

 

I'm using the Pirelli Scorpion Zero tires and am very happy with them. I don't care if they are a so called SUV tire, they work well, are V-rated, and are pretty sticky for a street tire. I think they also look pretty good, though I'd have the yellow scorpion mounted on the inside if I did it again...

Also keep in mind like was mentioned before, if you are driving at higher speeds you need to inflate your tires accordinly. Of course I don't consider 75-85 MPH fast myself and believe you could probably get by fine with 35 PSI at those speeds. For faster than that though I would definitely inflate higher, following the manufacturer's specs of course. They do spec these things. I had a chart for my tires somewhere, but I'm not sure what I did with it . . .

-dath

 

I am surprised that only 3 manufacturers support 15 inch tires with a speed rated series. I have to admit I was probably under inflated for the days temperature of 93 degrees. Not having a track temperature looking back based on what they tell you watching drag racing etc. The "track" was probably running heat soaked from the day about 115 to 130. The contact patch on those wide tires would contribute as well. My inflation on the other tires was 32 psi. Also I would like to mention how I got out of the dilemma of changing the tire. I'm in my mid 50's and was not looking forward to my removing the tire from the carrier on a hot day along side an interstate. So I limped into the next town [two miles away]. It was 7 in the evening and 99.5 percent of your gas stations offering full service are closed. This is where it gets good. I found a wal mart with a tire service still open at 7 on a saturday night and they did the swap for me. When I went to pay I asked how much and he said three dollars seventy two cents. My jaw just about hit the floor. I would have paid fifty dollars to have someone do that along side that interstate, wrestling the spare out etc. Anyway I pulled ten from my wallet and said buy all the guys a cold soft drink back there changing tires. The guy said no thanks. Wal Mart doesn't allow tips. I felt bad that I couldn't tip the guys for the consideration they gave me.

 

Tire Rack has good info re tire inflation for various speeds..charts and all...there is not much to it providing you are at rated cold pressures..maybe 2-3 psi more depending on speed/tire rating,rim load..etc..

 

I don't think it was just underinflation that caused your problem if you really were driving between 75-85 mph and having about 32psi. That sounds like bad tires to me, but I am no expert. I've never had that happen before and I drive in that range myself in my wife's car frequently. We just run Toyo's on that one . . .

I think there may also be some MT Street Radials available, but I hear they only last about 14K miles or so. If you don't drive too much, they'd definitely be worth checking out.

-dath

 

https://www.tirerack.com/tires/tiret....jsp?techid=72

Note that in the case of "S" rated tires the chart assumes 35 PSI (cold tire inflation)

My Yoko's are speed rated "T" for 118 mph 35 PSI cold tire inflation...

 

IMO, the best looking SR rated 15 inch tires that don't cost an arm and a leg are the BFGoodrich Radial T/A. They have a raised white letter that goes nicely with the old Stingray body stlyle. I use 275/50/15 in the back and 235/60/15 in the front. The 275/50 in back gives the car a nice aggressive look. A full set from the tire rack $335.

I've run these tires religiously a two of my cars for years and never had a problem.

These tires have great traction too. I've pulled consistant 1.80 sixty foot times when I've taken my '71 to the track.

 

Simmo, what is the Yokohama model line tire that you are running that is speed rated at 130 mph? I am assuming you are using the 255x60x15 size also? Thanks.

 

Might be these...
Yokohama Avid H4s/V4s ...215/65HR15 though...skinny,I'd say...

 

I'm running BFG 255/60's at the specified 35psi & almost exlusively run at 75-80mph (2000rpm with OD) for hours at a time (if I can afford the gas ). They're S rated, which I read somewhere was rated for 113mph. I've also read that H is rated at 130mph (in the m/cycle world we used to assume S was about 90mph & H was 120mph - but a tire exploding on a m/cycle is a serious problem so a saftey margin is a good idea). I have had a front tire explode at 120mph on a car & it really isn't funny. Not one little bit. Speed ratings are crucial for safety, as no matter how good your suspension, brakes, etc, it's still the tires that your life is depending on.
Originally my Vette was fitted with 225/50 (60? 70? whatever it was) tires and swapping to 255/60 made a difference in handling (it follows ruts a lot more, causing it to feel twitchy). This would back up a conversation I had in the summer. A Vette specialist here (Corvette Kingdom) have years of experience with Vettes & are running 215's on theirs as the handling is vastly improved. They use a Pirelli tire (not sure which, but I could find out if needed). This tire "fills" the wheel well & looks OK from the side (looks skinny from the rear though) & they're adamant that the thinner tyre vastly improves the handling compared to the wide tyres that most people fit (but the 255/50 BFG's do look good ). They would run 225s if needed, but prefer the 215s and wouldn't touch 255s with a barge pole. We do have much more twisty roads here than you guys, but a sports car is meant to go around corners well, so my next set of tires may well be thinner for the improved handling (although I love the look of the wide tires and I AM a tart when it comes to me Vette :lol). I'll certainly use modern rubber for the next set, whatever size I choose, & Pirellis are looking like being favorite.
A forum member (Gator81) has swapped his BFG 255/60s for a set of Pirelli Scorpion zeros of the same size. While he was a bit reluctant at first, as they're a truck tire & the tread pattern looked like a truck tire, he was impressed with them. He described them as feeling like somebody had wrapped his BFGs with a thick layer of velvet as the ride quality was vastly improved (though the BFGs may have been old & hard). Additionally, the Pirellis have much stiffer side walls which has resulted in him being able to take his favorite bends far faster than ever before as they grip well beyond the point at which the BFGs would have been squeeling as they lost grip.
Tires shouldn't fail at the speeds yours went at. The only reason I've known for that to happen is if they're being run at low pressure (or have previously), a manufacturing defect (unlikely), or if the alignment is bad, causing a lot of heat build up. There's probably many more reasons possible, but those are the ones I've "known" personally.

 

Michelin offers the TB15 (soft) and TB5 (medium) tires in 15 inch performance sizes that are V rated. Get your wallet out...
http://www.michelinsport.com/sport/f...ue=600&lang=EN

 

wow that's the first time I've seen "good traction' and 'Radial T/A' used in the same sentance!

I wonder what kind of times you run with a stickey tire