I want to put runners on my 66 and save the bias goldlines for show. I bought 7 x15 cragers to replace the k.o's, but am getting conflicting info on the radial size i need. I want the biggest and widest tire I can put on w/o rubbing obviously. I think I've nailed it to a 205-75-15, but recently was told a 235-70-15 would work as well. I'm looking at Dunlop Radial Gt qualifiers as this is what's on my 71 camaro as well and they work and wear great. Can anyone advise?
-
-
Re: Replacing Bias Tires on 66
Eric-----
It's hard for me to believe that a 235-70-15 would fit your car, but I can't say, for sure, that it won't. This tire is almost 2" wider in cross-section than the original tires, although its diameter is about the same. Usually, mid-year wheel wells won't accept tires much larger in cross section or diameter as compared to the original tires.
Your choice of wheels also further complicates the fitment situation. A 7" wide wheel is 1-1/2" wider than the originals used for your car. By itself, I don't think that this would be a problem, ASSUMING that the offset is close to the original. However, in combination with a 235-70-15 tire, I think that there would be interference problems.In Appreciation of John Hinckley -
Re: Replacing Bias Tires on 66
Joe-
Thanks, I think you're right. The offset on the crager s/s is almost Identical compared to the k.o.s ..I think I will go with the 205-75-15s or a 215-70-15. Both seem to be comparable. I am having trouble finding a good selection on radials in the 205-75-15s..particularly with raised white lettering. Any suggestions?Comment
-
Why not get a set of goldline radials? *NM*
Comment
-
Re: Replacing Bias Tires on 66
Eric----
The selection of 15" tires in 75 and, even, 70 series is becoming less all the time. The police pursuit tires that Duke Williams describes in his recent Restorer articles might be a viable option for the time being. Keep in mind, though, that the Ford Crown Victoria which has become virtually ubiquitous for police service in all 50 states uses 16" tires. So, how much longer the tire manufacturers will continue to produce police pursuit tires in 15" size is anyone's guess.In Appreciation of John HinckleyComment
-
Re: Replacing Bias Tires on 66
The tire size you can install on a C2 has as much, if not more, to do with wheel offset as tire size. When Chevrolet increased the width of the rally wheels to 7" in '68 from 6" in '67 the '68 offset was changed to -0.28" from the +0.60" of the 6" Rally and KOs (including adaptor.)
Offset had to be moved in the negative direction in order to provide sufficient running clearance between the rear spring and wheel/tire, and because the offset was moved about a third of an inch in the negative direction, you can't run '68 Corvette 7" Rallys on a C2 without t******* the fender lips.
A 215/70R-15 matches the OE 7.75-15 in revs per mile, so speedometer/odometer accuracy will not be affected and 6" is adequate width for a 215/70. They should fit most C2s (mounted on KOs or 6" Rallys) that have nominal body and chassis dimensions. The 225/70R-15 police pursuit tires are on the ragged edge for a 6" wide wheel and whether they fit interference free on a C2 mounted on 6" Rallys or KOs will come down to a case by case basis. Outside clearance will be the critical factor and it can be improved by running negative camber in front in addition to the rear.
Given the unknown offset of your aftermarket 7" wheels, regardless of the size tire you choose you will be somewhere between a rock (fender) and hard place (rear spring end) with little or no room to maneuver.
DukeComment
-
Re: Replacing Bias Tires on 66
I'm running 225-70X15 on knock-offs on a 64. Plenty of room. Never rubbed, but they look too large for the car.Comment
-
Re: Replacing Bias Tires on 66
I have 225's Goodrich T/A's on the back of my 67 on original ralley wheels. They would not fit the front without rubbing so I have 215's on the front. Also, 225's won't fit in my spare tire boot, and 215's are a real tight fit.Comment
-
Re: Replacing Bias Tires on 66
Drum brake C2s have about 0.6" less track front and rear than disk brakes models, so running 225/70s on KOs on a '64 has a better chance of clearing the fenders than on a disk brake model.
Six inches is the minimum recommended wheel width for 225/70s, and I can imagine they look a little pinched, but they are the same OD and revs per mile as the OE 6.70-15s.
DukeComment
-
Re: Replacing Bias Tires on 66
If you set the front camber somewhere between 0 to -1 degree, 225/70s would probably clear the fenders. A change in camber of one degree in the negative direction will increase fender clearance by about one-quarter inch. The OE spec for C2 front camber is +3/4, so even going to zero will increase clearance by nearly a quarter inch.
The other clearance issue with wide tires on 6" OE type wheels is the tires rubbing the steering gear carriage bolt heads at full left steering lock, however, since you only use maximum steering angle at parking lot speeds, it's not a safety issue, and it won't do any damage other than rubbing off the paint.
DukeComment
-
Like I said...
You can put P205/75R15 goldline radials on your car and get the "look" and the performance, without worrying about clearance.Comment
-
Re: Like I said...
The problems with ALL 205/75R-15 tires is that they are decided LOW PERFORMANCE tires. No doubt they are superior to the bias repros, which are absolute junk, but the highest speed rating for a 205/75 is T and they have rock hard compounds.
There are a few performance oriented seventy series tires that have speed ratings up to W, but you have to be willing to accept blackwalls or a narrow whitewalls. There is also an outfit that has been discussed that can apply a sidewall treatment of your choice to any blackwall tire.
Speed rated seventy series tire will provide better handling and safety. They won't cause vibration because of out of round, and they won't disintegate on a hot day at 80 MPH on the freeway, and if you have an opportunity to explore high speeds you can do it with confidence, knowing that your high speed rated tires are of much higher quality than what are installed on trucks and SUVs.
DukeComment
-
Duke - What tires do you run on your '63? *NM*
Comment
-
Re: Replacing Bias Tires on 66
Just in case anyone was wondering: I'm going with a Dunlop GT Qualifier T 215-70-15. I've run the 65 series for years on my second G Camaro, and they've handled well. (I bought them at the Tirerack.com for $54 a piece. I'll let everyone know if they eventually do fit, and if there is any rubbing. Thanks for all the knowledge and input!Comment
-
Re: Duke - What tires do you run on your '63?
In order to answer this question I have to give you the entire history, so bear with me.
I chunked the OEM 6.70-15 General Jetaires the first time I took it to Kent to do hot laps when the car was only a few months old in the summer of '63. They were okay for the street until the next season, but I embarked on a tire search. The the final candidates were the Michelin X, Pirelli Cinturato, and Goodyear Blue Steak Sports Car Special, a popular racing tire of the time, which was streetable. In my heart I wanted the Goodyears, but my brain said Michelin because they would last longer and work better in Seattle's frequent rain. They also turned out to be great snow tires - climbing hills like a snow cat. I used to drive by stuck V-dubs and Corvairs.
The Michelins provided excellent service - great grip, excellent wear, and they made it through several more hot lap sessions at Kent with no ill effects over the next four years. Their one weakness was sudden break-away characteristics, which I found out about in a very big way twice - once when the road was wet, and once when I was wet. That last spin in 1966 about a mile away from my parents house in Seattle was the last time I lost control of a car having since gone on to a couple of years of SCCA racing, a couple of open road races, and countless hot lap sessions in all my cars ever since.
By early 1968 as I was near graduating from the U. of Washington in June and leaving Seattle and wanted to replace the Michelins, which were getting rather thin on tread. (The final mileage number was 47,000 - truly impressive longevity). Pirelli lauded the fabric belted construction of their radials as having much more gradual breakaway characteristics than steel belted radials. They had also just introduced a new Cinturato that was a low profile tire. The size/speed rating was 205HR-15, but they where about the same dimensions as a contemporary 225/70R-15.
I bought a set, installed then on the OEM steel wheels and was disappointed. They didn't work as well as the Michelins. Further investigation and discussions with Pirelli revealed that such wider tires need wider wheels. It made sense, and the new '68 Corvette was equipped with 7" wheels that were good candidates. My friend Steve (original owner of the infamous "12-mile L-88") got trade prices at Alan Green Chevrolet ordered a set for me.
I was concerned about fender clearance, and it turned out to be the case. I had to trim the fender lips - just the reinforcements that project horizontally into the fender wheel - no change to the visible contour. It was 1968, and this was necessary to keep the handling contemporary with the best available contemporary tires.
On the 7" wheels the Pirellis were absolutely superb. Nothing short of a real racing tire could even come close. In a handling contest the new '68 with bias ply F70-15s was an also-ran. I subsequently replaced them with a set of 225/70VR-15 Cinturato CN 73s, and I will replace these with a set of V-rated Firestone PV 41s in the same size - one of the police pursuit tires I discussed in my tire article.
I learned at a very young age that tires are the foundation of a car's handling characteristics. You can do whatever you want and spend untold sums on your suspension, but if you have low performance tires you will have low performance handling.
Since I made this modification 35 years ago and it is part of my car's and my history I am not going to undo it, but I certainly do no recommend that others trim the fender lips, and I would not do so today. There are wheel/tire solutions today that will be almost as good as a speed-rated 225/70R-15 on a seven inch wheel, but you don't have to modify your car to install such a combination.
One other tire note. The first set of Cinturatos - the set that I installed in '68 got me through Lookout Pass in Idaho in January of '71 after I finished grad school. After driving all the way from Madison (WI) I decided to RON in Missoula and do the pass in the morning. It was midnight and starting to snow. I arose at 0600 and hit the road with the snow getting deeper. I drove right by a chain check point, and as I ascended into the pass it turned to a near whiteout. Only the hazy rut between the two huge bearms of plowed snow defined the path. I saw the outlines of at least two semis off through the bearms and into the ditch. From the chain check point I didn't see another operating vehicle in either direction. For a while I feared that if I went off the road they wouldn't find me until spring! I was maintaining 25 MPH in second gear and was treating the throttle like an egg. If I tried to accelerate even by the slightest amount I broke traction. If I lost momentum I would never gain it back.
Soon enough I passed the 4700 foot summit and was heading downhill. Very shortly the snow turned to rain and the snow covered road to a merely wet road. A few miles and about a thousand feet down from the summit I passed the line at the west side chain up area. The highway patrol officers looked at me slack-jawed as I drifted down the hill with the exhaust burbling on overun and no "clomp-clomp-clomp" from installed chains. People started cheering and waving, and I waved back.
Shortly after that the Coeur d'Alene radio station I was listening to interrupted normal programming with a news bulletin: Lookout Pass was closed- indefinitely! I think the Pirellis were a good choice.
DukeComment
Comment