Originally Posted by aray67
Hey does anybody have any recommendations on what size tire i can upgrade to, I would like to go bigger without mods on my 11 Grand Cherokee with stock 18's(265/60-18) looking at Cooper Discoverer HTP
You can go to a high volume tire outfit like Goodyear, Discount, or Big-O, and tell them you would like to purchase the largest tire you can for your vehicle. They'll tell you what it is. You can do all of this by phone, and get prices at the same time. The tire business is VERY competitive today, and they'll be more than happy to accommodate you. Most of these places won't mount an out of spec tire on a vehicle because of safety and liability reasons, tire damage from rubbing, and so on.
They can also answer questions about speedometer error, transmission shift point changes, tire pressure, etc. This is all important to know before you change out to a larger size from a different manufacturer. When I drove my 1991, 5.0 Mustang for almost 24 years, I had a multitude of different size tires on it during that time. Taller, wider, etc. Tire pressure alone varied from 32 PSI to 44 PSI in all of these. So it's important to get as much information as you can before you make the change. This is why I say it's so important to go with information that's molded into the tire sidewall. Not what's on some sticker in the door jamb, that means nothing to a different size and make aftermarket tire.
When the OEM tires were gone on my Mustang, (Goodyear), the tire place I went to tore off the door jamb sticker because it no longer applied to the tires I had installed, (Nitto). They did the same when the original tires on my truck went away, (Firestone), and were replaced by larger 31 X10.5 x 15 Remington's that had a maximum cold inflation of 50 PSI as opposed to the 32 PSI on the OEM P235 X 15' Firestone's that weren't even LT rated. They couldn't believe Ford sold the truck with those tires.