C2 tire size

[BarryK]

ok, ok, I know this issue has been beaten to death on all the various Corvette forums but as I searched I never saw a direct answer for this particular tire size question.

I need to replace my tires on my '65 coupe this winter and I'm currently running 205/75/15 Goodyear Invecta's which were on the car when I bought it. I'm noticing some waviness along the sidewalls and I'm just not at all happy with the performance of the tire. I also get just the slightest amount of rubbing at full turn lock against the frame rail. Just enough rubbing to put a mark on the frame but that's it. I'm assuming the rubbing is because the 75 aspect tire is a bit taller than the standard 70 aspect.

I'd like to run Goodyear Radial GT's in 235/60-15 which my neighbor had on his '67 with no problems.
I currently have the stock steel wheels but also plan on upgrading eventually to the repro bolt-on KO's.
My desire is to have a wider tire for a nicer and "tougher" look to the car and also try to improve the handling a bit but obviously don't want any rubbing issues.

I did a search comparing the standard 205/70-15 against the wider 235/60-15 and came up with these numbers:

205/70-15:
Sidewall: 5.6"
Radius: 13.1"
Diameter: 26.3"
Circumf.: 82.6"


235/60-15:
Sidewall: 5.6"
Radius: 13.1"
Diameter: 26.1"
Circumf.: 82.0"

Between the two sizes, the sidewall and radius compare as the same, and the 235 tire has just slighter smaller diameter and circumferance. Based on that, I'm figuring it should fill up the wheelwell almost as much and should also eliminate the slight rubbing I'm getting on the front frame rails but not create rubbing elsewhere and will give me the wider look i'm trying to obtain.

Any comments?
Anyone else running 235/60-15's that can comment or say if my calulations are off?

if I really need to I could drop down to a 225/60-15 but a lot of this choice was based on the looks and the fact that there were no rubbing issues at all with the 235 tire on my neighbors car.

thanks for your help.

Barry

 

[jakenjake]

I have 205/70-15 (Perallie 4000's (sp?)) on all corners of my 67. They actually look a little small on the car. If I were going to do it again I would put 215/70-15 at least on the rear.
John

 

[BarryK]

John, I agree, the 205's just look a bit "skinny" for my tastes which is why i'm looking to go a bit wider.
i'm afraid of going much wider with a 70 series tire though for rubbing issues and figure to go wider it may be best to go with the 60 series instead

 

[JohnZ]

I did a search comparing the standard 205/70-15 against the wider 235/60-15 and came up with these numbers:

205/70-15:
Sidewall: 5.6"
Radius: 13.1"
Diameter: 26.3"
Circumf.: 82.6"


235/60-15:
Sidewall: 5.6"
Radius: 13.1"
Diameter: 26.1"
Circumf.: 82.0"
Barry

Barry, you missed a key dimension - overall section width. The 205/75-15 you have now is 8" wide, and the 235/60-15 is 9-1/2" wide; that's 3/4" more section width on both the inside and outside of the tire relative to the frame and the fenders (which have your new $$$ paint on them). Also, the 235/60-15 absolute minimum recommended rim width for bead seal and retention is 6-1/2" (yours are 5-1/2"), with 7-1/2" recommended for proper tread contact patch shape. The 1" difference in diameter between the two will also introduce another 4% speedo error. Just a few more things to consider when thinking about tires on a midyear; you can't just pick what "looks good".

 

[paul67]

Barry,
My answer is over at NCRS but basically says what John has said with less eloquence.

 

[BarryK]

John
yes, I realized after someone responded to me elsewhere that I didn't take into consideration that the 235's wouldn't even fit on my stock steel wheels and that my neighbors '67 Rally wheels are wider.
This is very disappointing as I really want to get a tire that has a much better look and is wider but also NO rubbing or hitting issues of course. Well, I guess the 235's are definately out.......... sigh. And they looked so good on his '67 too!

well, back to the research again, maybe 215/65's ??

Paul, was that you that responded to me on the NCRS board that referred to the same "neighborhoods"? I was wondering about that comment.
oh, i just checked the board again and I see it was you.

 

[ctjackster]

As always, John has said this but methinks you might get a rub with the size you are thinking of. As you know, I am running 215/70R15s with no rub, although some HAVE reported a possible rub at full lock and full compression (i.e. if you were turning hard into a driveway that had a slight curb to its lip)

you know where to see a pic of my car with that size on it.

 

[BarryK]

thanks Jack
yep, the 235's are definately out.

i'm surprised you can run a 215/70 with no rub since i get a slight one with my current 205/75's. I guess the slight difference in the series is just enough. I would have thought to even go to 215's would have required the 215/65's.

well, i'll search the archives some more and just re-review the previous answers to decide on a size now that this plan is shot.

Thanks all

 

[ctjackster]

I think you would find many are running 215/70R15s with no problem, maybe do a poll??

 

[BarryK]

Jack
I'm not a big fan of "polls".
checking again thru the archives i've also come up with the 215/70-15's as about the most common and popular size behind the "standard" 205/70-15's.
As much as I really wanted a somewhat wider tire, i'm not willing to go to a larger "modern" wheel size such as a 17" to do it. I've seen them on many cars and they are nice but just not MY taste so I'm stuck with what works on my stock wheels (and eventually the bolt-on KO's I want to get), so I think the 215/70-15's are probably it.
At least the tire size is "safe" for rubbing issues and my bodywork and paint.