One thing nobody touched on;The profiles.Its pretty easy to put a huge width 80 series tire on a skinny rim. Oops wheel(sorry).lol
You could probably put a 275/80 on a 5.5 inch. But just try putting a 275/50 on that 5.5er.
Furthermore is tire pressures. If you were to put that 275/80 on that wheel, then to get the tread flat, you might have to run 12psi. Just try cornering on that.
There is a very definite science to fitting tires to rims.Thats one of the reasons we have the charts and the formulas. With a good match, you can run a comfortable tire pressure,get a full life out of the tread, be able to corner,tow,jack-rabbit starts, etc, without killing the tires.
Just because you got a tire on it, doesnt mean you will get full benefit of that tire.
If you put a too wide-for-the-wheel, tire on it, and the profile is a bad match, the edges of the tread will pull away from the road at a normal tire pressure. This causes the tire to wear off the center prematurely.If you catch it before its too late, you can reduce the tire pressure. This can lead to a situation where the center of the tread buckles up, and wears at a slower rate than the rest of the tread. And the low pressure can lead to handling issues.
If you put a too-narrow-for-the-wheel, tire on,and the profile is a bad match, it becomes harder to get the edges of the tread on the road, at normal tire pressure.
-The point is;one can deviate from the charts, if your willing to juggle; the profiles,and air pressures,and tire life,and handling,etc.
-If you just want to put the tires on and forget about it, Try and stick to the chart.
Yeah, 195s are some pretty skinny rollers.A 5.5 inch rim is 140mm in metric-speak.
There is an earlier post on reading the tire sizes.
Unfortunately, when we went to the metric sizing, the tread width didnt translate. Instead, that first number is a section width. Furthermore it is a section width on a specified rimwidth. The tread dimension isnt even part of the tire code.
Say you have a 235 tire.The specified rim width is 70% of that, which would be 165mm,which is 6.5 inches.Wait,you say. Where did I get that number.From the tire chart. So a 235 is to go on a 6.5 inch rim.If you put it on that rim,the section width will be very near to 235mm. What will the tread width be? Who knows, there is no spec for that. But generally speaking, the tread width will be very close to the specified rim-width.
So lets work backwards from 5.5 inches
A 5.5er is about 140mm. At 70%, the section width would be; 140/.70=199.5mm. Commonly rounded down to 195. So the correct section width tire for a 5.5er is 195. But wait. the section math is 199.5mm. Well aint that sweet. A 205 tire could be considered normal just as well. So now we have a working range of 195 to 205 as the standard section width for a 5.5er. Phew
Now lets consider profiles.
Say youve got your heart set on putting a wider section width tire on that 5.5er. Well, the taller the tire profile, the easier it will be to run the tread flat to the ground with a normal tire pressure.Conversely, the lower the profile, the harder it will be.
So, Im gonna go out on a limb here.If you want to run a 50series tire, you better stick to 205max. A 70 series could fit a 215. A 80 series could probably fit a 225. These are at a normal tire pressures. Check you door sticker. This would probably be near 30psi
If you are willing to juggle tire pressures, you could probably run the next larger width tire on each profile, but might experience premature tire wear-out, or odd tire-wear, or handling issues.
- So that would get you a 225/70 on that skinny 5.5er. Probably at 26psi(guessing). Thats doable, but easy on the cornering until you learn the tire-quirks.
Hope that helps.
