QuestionOn a Dodge Ram Truck, 1/4 ton, we are told we have 17.5 inch rims but the tires on the vehicle are 17 inch. We see a danger notice on the tires not to mount on 17.5 inch rims. What is the danger and why would a reputable tire dealer put 17 inch on 17.5 inch rims. How can we determine if they are actually 17.5 inch rims?
AnswerKaren,
On every vehicle sold in the US, there is a sticker – commonly called the 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.
I think if you locate the vehicle tire placard, it will tell you they are 17" rims. But in case it does tell you they are 17.5" rims, then IMMEDIATELY go back to the dealer and explain to him what you suspect. Drive slowly and careful, avoiding sudden acceleration and braking and take the corners extremely slowly.
The real danger is in the mounting process - and hence the warning, which is directed at the mounting machine operator.
However, 17" tires are not compatible with 17.5" rims and 17" tires will not properly seat on 17.5" rims, and are only held on by the pressure in the tire.
Unfortunately, rims are usually marked for size on the inside and the wheel must be removed from the vehicle to see them.
