Tire Pressure for Non Stock Sizes

[mluder]

A few months back I replaced my tires for shiny new BF Goodrich Radial T/As (love me some raised white letters).
As they do not offer stock sizes for the fronts I went a little bigger with 215-60r14 and 245-60r15 in the rear to balance the look.
Now with that said, I understand that tire pressure would/should not be the same as stock as different sized tires require different inflation based on vehicle weight and some other math.

Anyone have any advice on calculating this? The few articles I've seen online have left me confused.

Cheers
Steve

[spaceboyusa]

Run the same tires/setup and would be interested as well. Pretty sure I'm running 27/33 in mine right now but to your point, from memory, none of the previous threads really address larger tires in the front and rear.

Count me interested in some feedback on our setup.

[David T]

Start out using the recommended pressures and measure the tire tread often with a tread indicator. You can buy them at an auto supply, they are not expensive. Measure the tread in several places across the tread, ie, the sides and the middle. Depending on how they are wearing you may need to increase or decrease the pressure. The aim is to get the tread to wear evenly across the middle and the sides. Also get a GOOD tire pressure gauge so you can accurately measure the pressure.

[mluder]

Start out using the recommended pressures and measure the tire tread often with a tread indicator. You can buy them at an auto supply, they are not expensive. Measure the tread in several places across the tread, ie, the sides and the middle. Depending on how they are wearing you may need to increase or decrease the pressure. The aim is to get the tread to wear evenly across the middle and the sides. Also get a GOOD tire pressure gauge so you can accurately measure the pressure.

Finding an accurate gauge is right... Any recommendations on a tire pressure gauge?
I have several but they all disagree with each other.

Cheers
Steve

[David T]

Finding an accurate gauge is right... Any recommendations on a tire pressure gauge?
I have several but they all disagree with each other.

Cheers
Steve

You have to spend more than $5. I have one I bought from Griot's Garage but you can get a good one at a lot of places. Look up racing products. Figure on spending at least $30 and don't drop it. I prefer the analog but digital is good too. You just have to feed it batteries. You must be able to read to the 1/2 lb.

[Josh]

Can you post a picture of your car? interested to see what the 215s look like. just put bfg 245s on the back last week.

[mluder]

Can you post a picture of your car? interested to see what the 215s look like. just put bfg 245s on the back last week.

Sure -
I'd love to but it looks like the message board isn't allowing me to post them. I can select the file but then I don't get an OK button to actually load it.
I'll try again later.

A couple of things...
I do get some rubbing of the front tires on the front edge of the wheel well arch. Only happens under certain loads. Specifically when I'm backing out of my drive (down hill) and the wheel is turned just right. No damage done except to the safety trim strip inside the wheel arch. The rest of the time, nothing. I know another person with the same set up but the car is lowered and he has no problems with rubbing. My car is stock suspension.

I think lowering my car would definitely look a bit better and might alleviate the rubbing. Just don't have the funds for it yet.

Cheers
Steven

[David T]

There is another method to figuring out tire pressure. Using an infra-red thermometer, you read the temps of the tire tread, each side and the middle. The goal is to get the temperature even across the tread. If, for example the center of the tread is hotter than the sides you have too much pressure and the tire is bearing most of the weight only on the center of the tread. You will see this a lot faster than waiting for the tires to wear and measuring the wear.