Date: Fri, 11 Apr 1997
Glenn,
I have been a member of VSA [Volvo Sports America car club] since 1983 and occasionally see articles on what sizes of tires work safely on the 1800ES. I have a '73 and am in need of new tires. I currently have 185/65R15s on and will be glad to get rid of them. No top end, and also screws up my speedometer reading. 185/70R15s are stock, but hard to find. I am considering 195/70R15s or even 205/70 or 205/65 since they (the 205s) are easier to find. Can you tell me what sizes will work safely and any recommendations you might have for brand? All of my driving is done on flat highways and city streets.
Thanks.
Phil Lehr
plehr@intermind.net
Phil-
Generally, I say stick to the stock size if possible. You don't always see stock sizes advertised, but many tire shops can order them from a warehouse if they don't have them on hand. Failing that, try to find the next closest size. I would not try anything larger than 205, and I would not be happy if I had to go that high. Larger tires are more difficult to balance and harder to steer than stock tires. You also might have trouble with them contacting the wheel wells and fenders.
Don't deal with a tire store that won't try to find the correct size. If they won't do that, there are probably some other things they won't do for you. In particular, don't let them remove your old tires until you have inspected the ones you are about to purchase.
Accurate speedometer readings depend on the total diameter of the wheel-and-tire assembly, which can be calculated from the figures in the tire size, although for comparing the effect of tire size on speedometer readings, the tire profile is more convenient to use. To calculate the profile (the distance from the wheel rim to the crown of the tire), multiply the first figure in the size by the aspect ratio, assuming the aspect ratio is a percentage.
For example, if the stock tire size is 185/70, 185x70%=129.5, so the crown of the tire is 129.5 millimeters from the wheel rim. If you put 185/65s on the car, the profile is going to be 185x65%=120.25mm, a difference of 9.25mm. If you put 195/60s on it, the profile will be 117mm, a difference of 12.5mm from stock. Looks like the 195/60s will throw your speedometer off even more than the 185/65s, although in the other direction.
As far as brands go, I can recommend Michelin and Toyo, which I have used, and any other well-known brand, although I'm not partial to Firestone. My dad got burned on their 721 radials. I saw a comparison in Car & Driver magazine several years ago that showed B.F. Goodrich was also a good brand. Keep away from cheap brands, and even cheap tires from well-known manufacturers. I bought some cheap tires from Pep Boys several years ago because I didn't see the correct size advertised anyplace else. Two of those tires suffered blowouts when I turned the steering wheel while the car was sitting still!
For more recommendations, try Consumer Reports. They do good comparisons and testing (if you can find an issue with tires in it), and Car & Driver occasionally does tire tests. -Glenn.