Tire Pressure for upsized tires/wheels

[gdizzle]

So I upgraded the 66 DDArt from 13in, to 14in. Went upto 205/75. My 13's were 185/70.

This is my question, the suggested tire pressure from the manual says 24psi? That just seems to soft.

Now that I have the 14's, and they are a little wider/taller, does that mean I need to increase PSI or just keep it at 24?

 

[ChrisPerry]

All things equal, larger tires require less air to hold up the same weight.

That said, the width of the rim as compared to the width of the tire can dictate how much air pressure you can run and get an even tread wear pattern.

Narrow rim and wide tire.....need to run lower pressure to get the tire tread to make full contact with the road (center touches,sides don't). This will give a cushy ride, but will cause wallowy handling.

Wide rim with a narrow tire.......need alot of pressure to get the tire to wear evenly (sides touch,center doesn't) rides rough and can cause loss of traction

I prefer the wheel to be within an inch +or- of the tires tread width. (best compromise between ride,handling,and wear)

I then air them up to full pressure,scribe a chalk line across the tread and drive forward with the wheels perfectly straight. (be sure you are on smooth pavement) keep airing tires down a little at a time until the chalk wears off the full width of the tread. Most smaller cars end up between 26-32psi low pro tires usually take more.

EDIT......be sure car is loaded the way you normally will be driving it. Front and rear tires may or may not take the same amount of pressure.