Another tire question

[Duke W.]

Re: Another tire question

Static OD is not that precise. What counts is loaded revs/mile, which is listed in the "specs" section for all tires at The Tire Rack and the manufacturers' sites.

For reference the loaded revs per mile spec for 6.70-15, GR70-15 and 225/70R-15 is equal to or very close to 760 for all tires in these sizes; 7.75-15 and 215/70R-15 are similarly close to 775. This spec must meet a very narrow range for each tire size as promulgated by The Tire and Rim Association.

C2 speedo gearing was established for 1963 based on the 6.70-15 and carried over for subsequent 775 revs/mile tires, so any 775 revs/mile tires will increase error by about 1.5 percent on most C2s and C3s

Loaded revs/mile is what you should try to match as close to OE as possible, so anything in the range of 760 to 775 is in the ballpark.

I wish I had a nickel or dime for everytime I've explained the above.

Duke

[Patrick H.]

Re: Another tire question

I wish I had a nickel or dime for everytime I've explained the above.

Duke

Yeah, like that never crosses my mind when talking to patients.
Some days I, too, feel like I'm going "blah, blah, blah" when I'm talking.

Patrick

[Jim T.]

Re: Another tire question

Jamie do you have a secret on how to install a trim ring attachment on top of a wheel weight?

[Jamie F.]

Re: Another tire question

No secrect, just got lucky and none of them ended up in the 12-3-6-9 o'clock positon with the clips!
I guess I should have read every part of the TIM&JG before I had them mounted and balanced. Oh well, how many points deducted is that going to be? They did use the correct Micro weights though...

[Kenneth H.]

Re: Another tire question

So, in a number of previous posts I've noticed that almost unanimously eveyone says that the Kelsey Goodyear Widetread F70-15 tires are the best repros for judging. However, the specs for these tires are substantially different than the specs listed in the Judging Guide for original Goodyear Widetread F70-15 tires (Section Width - 8.95" vs 8.35", Overall Diamenter - 26.97" vs 26.92", Tread Width - 6.5" vs 6.26"). Or am I misinterpreting the "approximately equal" comment in the JG as being too strict from a specifications standpoint?

When I compare the Goodyear Eagle GT II P225/70R15 tire to the Kelsey Goodyear Widetread F70-15 repro tire, the specs are similiar. Does that mean that a Goodyear Eagle GT II in P225/70R15 size would be an acceptable radial replacement tire for the original F70-15 tire for judging purposes? And what about the raised white letters on the GT II? They are substantially larger than the letters on an OEM Goodyear Widetread tire. How will that affect the judging of the tire?

Finally, since BF Goodrich was not an OEM tire supplier in 1970, if I choose to purchase the BF Goodrich Radial T/A in P225/70R15 size, will I receive a greater deduction than I would with the Goodyear radials listed above?

[Jeffrey S.]

Re: Another tire question

Ken:
I have 225's on my '69 but I know of several early C3 owners who have had problems with 225's being too large when fully turning the wheels. If you know anyone who has a set of these you should try to test them on your car. If I was to do it over again I would use the 215's. Just my opinion and I know others have suggested the 225's.
Jeff

[Pat M.]

Re: Another tire question

Ken:
I have 225's on my '69 but I know of several early C3 owners who have had problems with 225's being too large when fully turning the wheels. Jeff

It is true that if I turn the wheel as hard as I can I do get a SLIGHT rub at the bottom/rear wheel well with the 225s. But I rarely need to turn that hard and now instinctively don't do so.

[Gene M.]

Re: Another tire question

Patrick,
How does the tire to fender clearance at both the front and rear bottom corners at the front tire with it at full lock to lock look. The 215/70-15 is about 3/4" smaller diamter than the 225/70-15 tire. Do you have both these sizes on your cars now to measure? I have a 72 in my garage now with G70-15 old /michlen radials and right side at full lock to the left just touches the lower front fender lip. Tire diameter is 27 1/4". A new 215/70-15 GY is cataloged at 26.9" I hope this would fit and not hit the fender. Ideas............?

[Patrick H.]

Re: Another tire question

So, in a number of previous posts I've noticed that almost unanimously eveyone says that the Kelsey Goodyear Widetread F70-15 tires are the best repros for judging. However, the specs for these tires are substantially different than the specs listed in the Judging Guide for original Goodyear Widetread F70-15 tires (Section Width - 8.95" vs 8.35", Overall Diamenter - 26.97" vs 26.92", Tread Width - 6.5" vs 6.26"). Or am I misinterpreting the "approximately equal" comment in the JG as being too strict from a specifications standpoint?

When I compare the Goodyear Eagle GT II P225/70R15 tire to the Kelsey Goodyear Widetread F70-15 repro tire, the specs are similiar. Does that mean that a Goodyear Eagle GT II in P225/70R15 size would be an acceptable radial replacement tire for the original F70-15 tire for judging purposes? And what about the raised white letters on the GT II? They are substantially larger than the letters on an OEM Goodyear Widetread tire. How will that affect the judging of the tire?

Finally, since BF Goodrich was not an OEM tire supplier in 1970, if I choose to purchase the BF Goodrich Radial T/A in P225/70R15 size, will I receive a greater deduction than I would with the Goodyear radials listed above?

1. Yes, the numbers are "close enough" since I have yet to pull out a tape measure on the judging field.

2. As noted in a previous post, the 215 is the size listed as "accepted" in the JG. When the next 70-72 revision gets going I'm going to lobby to add the 225 to the list. However, for now the 215 is listed. You "may" get a judge to side with you but...

3. Yes, BFGs will receive a more substantial reduction. Please see the standard tire deduction notes in the Judging Reference Manual.

Patrick

[Patrick H.]

Re: Another tire question

Gene,

My yellow car has 215s, my Dad's car has 225s. No issues with his given the limited miles he's put on it. I've never purposely checked the clearance with the steering at its limits.

Patrick

[Kenneth H.]

Re: Another tire question

OK. I had the new Radial T/A P215/70R15 tires installed yesterday and they fit fine on the 15x8 wheels. I absolutely cannot believe the difference the tires make when driving. My corvette is now a real sports car. It handles fantastic.

So now my next delimma. The incorrect Firestone Wide Oval Super Sport bias ply redline tires are now in my garage. I plan to sell them but I can't figure out which repro tire manufacturer made them. The tire guy who sold me the Radial T/As told me that he thought that the tires were made from the original molds, but that's all that he could tell. And how he knew that, I have no idea. Does anyone know of any way that I can identify the repro tire company that made these tires?

[Terry M.]

Re: Another tire question

Do they say "Sup-R-Belt" on the sidewall? This would be in raised letters.

[Jeffrey S.]

Re: Another tire question

There is a TIC (Tire Identification Code) on all tires. Let us know what it says and it can be decoded. If these were made from the original molds and have 7 treads then they were most likely made by the McCreary Tire and Rubber Co. and would have a CY code in a raised "panel" molded onto the tire. It would have other numbers attached but the code for this company begins with CY. Most of the later Sup-r-Belt tires I have seen are from this company.
Jeff

[Kenneth H.]

Re: Another tire question

Terry, yes, there is a raised "Sup-R-Belt" on the side of the tire.

Jeffrey, yes, ther is a TIC. It is CYU2F4161607.

Thanks.

[Jeffrey S.]

Re: Another tire question

Ken:
CY = McCreary Tire and Rubber, U2 = F70-15. The rest is a mystery to me. Could the last 4 digits-1607 = 160th day of 1977 or 1987?
Jeff