Tires: tire pressure, tire placard, goodyear eagle

Question
I recently purchased 4 brand new Goodyear Eagle Gts for my 2004 Ford Mustang GT, i noticed there is no cold psi info on the tire. It only says 51 psi. Is that where i air them up to cold? My last set of tires had 30psi cold. I dont want to over inflate them. Please Help! They are 245/45zr/17

Answer
Barry,

On every vehicle sold in the US - and I understand this is a worldwide practice as well - there is a sticker – commonly called the vehicle tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

BTW, it doesn't matter who makes the tire or what pressure is listed on the tire's sidewall, if the tire size is the same as the placard, then the pressure listed on placard is also appropriate.

If you are using a tire size that is different than what is listed on the placard, then the pressure has to be recalculated.  The calculation is not difficult, but it requires tire load tables which are not allowed to be published in the Internet because of copyright laws.  However, I have a copy and would be glad to do the calculation, but the starting point is the vehicle placard: Tire size and inflation pressure.  I will also need to know the new tire size.