don't know what tire size to get

[Gran Sport66]

I am in a conundrum-I have 215 70 R15 tires on my 66 Rivi now. Need to replace most of them, as two are cracked all over, (and also say "tubeless" on them, I assume that gives you an idea of how old they are!).
I can't spend a lot on tires, so I am looking for used. I found a set that are 225 75 r15, and was told that is the proper size for the car-the owners manual says "8.45 X 15".

What sizes would be best for these wheels? I know Joe uses 225 75 15, so I am inclined to just get these. I guess the car rides OK with these tires now 215-70, but it's all I know.

Any suggestions?

[gstewart]

if u have 15x7, i would go to 255r60x15 tires. they should fit & the handling & grip on turns will be significantly improved.
if u do not want the "60" series tire, then try the 245 or 255 x70 tire, if available.
the 845 tire could be a "78" series tire or could be an "83" series tire (narrower tread).
as an example, my 72 gs had a set of 275r50x15 bfg tires on a set of pontiac t/a snowflake rims. i decided to restore the 14x6 original rallye rims and installed 225r70x14 bfg t/a tires. the difference is like night & day. i went from fabulous handling down to good.
about to order a set of 15x7 rallyes from summit & will use 255r60x15 bfg tires.

[Gran Sport66]

Thanks Gerry.
Do you think this applies even though my Riviera is bigger and heavier? (than the GS you have) It's almost as big as an Electra or LeSabre. Similar in weight too, it weighs something like 4400 pounds.
Remember I have no clue really, and thought the ride in my car was OK. I don't know how much I'll be able test the limits of tire grip , etc. either, since I live in the city.
Thanks for the input

[BamaWildcat]

This site has conversions from old alpha designations to P-Metric:
http://clubs.hemmings.com/clubsites/chevylist/tech/tire_size_conversion.htm

[SpecialWagon65]

The 225-75-15 is a good stock size.
235-70-15 are slightly bigger and look very good.
I have bought both sizes used.

[gstewart]

in 1966, the tires originally on your car would have been polyester, rated at 4 ply but with only 2 plies of polyester. the new radial tires are much stronger & handle better & less liable to fail/blowout. are your rims 6 or 7" in width. if they are only 6" wide, then u are safely limited to 225r70x15 ; if they are 7", then i would go to 245r60x15.

[Gran Sport66]

Thanks all

I think the 235/70 are pretty rare, as I guess the 215/70 or 225/70 are also-someone from a tire shop told me that on the phone.

Any of you guys use Firestone Firehawk Indy's?

Any suggestions on brands that we should avoid?

[gstewart]

bfg's t/a radials come in 225r70, 235r70, 255r70, 285r70 all 15" .
firehawks are a whole different story.
s/b able to go to firestone's (bridgestone) website & check their tire sizes available.