Anyone have a good grasp on tire sizing? My 1981 Parisienne has 205/75R15's on it now. I'm hunting for a full set of snows for it before winter and I'm wondering what wiggle room I've got on sizing. The Mrs tells me that her grandparents have a full set of snows (4 + a spare) that they'll likely give me if I want them. They're 205/70R15's. If I were to change anything, I would have liked my snows to be a little wider, but I hate to pass up free tires without at least considering it a while. I can't see any issues from so minor a change, but I certainly don't have all the answers. Can anyone point me to some reading on the pros and cons of reducing my sidewall height/diameter a little bit?
Hubby seems to think that you will only be going down a bit in the wideth. He's saying snip'em up! Isn't it better to have a narrower tire in the snow?
Unless I'm way off, I think my width will stay the same as both sets are 205's, it's actually the sidewall that will be shorter so I'd be lowering the car maybe half an inch.
I work at a tire shop.and been in the tire business for almost 20 years. You have lots of room to put a 2157515,2257015 or 2257515 on there. Keep in mind the aspect ratio is a percentage of the width. 2057015 is .8 from 2057515....too much ..too small. Drops the car down,which may improve your center of gravity,but the handling will be sub par with less rubber on the road. http://www.miata.net/garage/tirecalc.html Hope this helps.
My 84 Custom Cruiser and my 86 Caprice, which are both the exact same wagon as your Pontiac, came from the factory with 215/75-15 tires. I'm running 235/70-15 BFGs, which are the same outside diameter but nearly an inch wider. The backs want to be wider still. Note that snow tires do NOT want to be wider. You want them narrow to get down through the snow, not to sit on top of it. These aren't supposed to be high-flotation tires.
I have 225/75/15 summer tires on the Caprice, and 225/70/15 for a winter tire. You can't really notice the difference, especially since we just putter around in the winter. The speedo will be off a little bit at highway speeds because of the smaller diameter. I say grab 'em, especially if the price is free.
Grab 'em. And Joe is right...you want narrow snow tires. They cut better and will take you where fatties won't.
First, a 205/70R15 is too small for the car. It likely won't have the weight rating, either. Personally, I have seen the best snow performance with a 215/70R15, but make sure they are a GOOD tire. Also, with the 'free' ones, how old are they? they are considered garbage 5 years after first being used or 10 years after manufacture, which ever comes first. Also, at the first sign of weather checking, they are garbage. I've had good luck with the GoodYear Nordic (for an el cheapo tire) and REALLY good luck with the Nokian Haakapilliitta (for a BLOODY EXPENSIVE tire).
Correction to my earlier post. The stock tires on both my 84 and 86 wagons was 225/75-15. This is the size that's the same OD as the 235/70-15. Sorry for the bad info. Note that the B-body sedans came with the 215/75-15s but the wagons got the 225s. I agree that the 205s are too small (and have too low a load rating) for these wagons.
I also agree that the tires are too small.... elephant on roller skates. Check the load ratings on the side walls. Mike
The reason I wasn't surprised at the 205/75s is that my brand new 84 Delta 88 coupe came with that size, in spite of being equipped with the factory handling package. They very quickly became a set of 225/70R15 BFGoodrich T/A Advantages. My brother had an 86 Parisienne Safari, and he ran a set of LT235/75R15 Pirelli Scorpion A/Ts for winter. He lives in the snow belt, and goes all over Hell's half acre. Never had any problem at all with them in anything less than 2 feet of snow. I still swear by the Nokians, though.
