You are here:

Tires/Tire size and replacement

Advertisement


Question
Can tire size P235/50R18 work to replace tire size P 245/45 R18?  I have a brand new full size spare and will be trading the car in as it needs a lot replaced.

Answer
Linda,

Maybe.

First, if the P245/45R18 is an XL (Extra Load), then the P235/50R18 also needs to be an XL (Extra Load).  The diameter of the P235/50R18 is 0.6" larger in diameter, so if this is going on an AWD (All Wheel Drive), that would not function as a single spare because AWD vehicles need to have identical tires all around (with some exceptions!)  If you don't keep the same diameter, then the AWD unit could fail and that would be very expensive to fix.

And lastly, the wheel width requirements have a lot of overlap, but if the wheel is 9" wide (probably not!), then the P235/50R18 will not fit.

Tires

All Answers


Answers by Expert:


Ask Experts

Volunteer


Barry Smith

Expertise

I have over 30 years experience in the design, manufacturing, and testing of tires. I have served as the technical advisor to the "800" number. I have authored or co-authored many publications - usually without credit. I can answer almost any technical question, but please don`t ask me to compare brands. I probably have prejudices because of my work experience.

Experience

Member SAE (Society of Automotive Engineers) Member Tire Society (Tire Technical Organization) SCCA Regional Competiton License holder Authored many training manuals on tires, their care and use.

Organizations
SAE (Society of Automotive Engineers) SCCA (Sports Car Club of America) Tire Society

Publications
You may want to visit my web site: http://www.barrystiretech.com/index.html

Education/Credentials
I am a graduate of the University of Dayton, Dayton, OH - BME, 1971 I attended graduate school at the University of Akron - but did not complete my PhD - something I regret.

©2016 About.com. All rights reserved.