Tyre Sizes Explained Technical Resources > Tyre Sizes Explained The very earliest of tyre designs were called Type I and were referred to only by their outside diameter e.g. 27″ which is a common fitment to aircraft such as the Harvard or P51 Mustang. General Aviation tyres are generally Type III designs and include the most widely used sizes such as 5.00-5 and 6.00-6. These measurements refer to the section width of a tyre and also the rim ledge diameter (or the hole in the middle) hence a 6.00-6 is 6 inches wide and sits on 6-inch wheel. Three Part Name Sizes cover most of today’s designs and typically describe the Outside Diameter, Section Width and Rim Ledge Diameter e.g. 15×6.00-6, the tyre is 15 inches tall, 6 inches wide and sits on a 6-inch wheel. Some tyres in this classification are preceded with an ‘H’ which identifies the tyre as having a higher percentage deflection. Metric sizes are the same as three part name sizes but the Overall Diameter and Section Width are replaced with millimeters but the rim sizes remain in inches, e.g. 380×150-5, its imperial equivalent is a 15×6.00-5. Radial tyres are also the same as three part name sizes but the dash preceding the rim diameter is replaced with the letter ‘R’ e.g. 32×8.8R16. Technical Data Type Tyre Size Overall Diameter in inches Section Width in inches Wheel Diameter in inches Type 1 27" 27" - - Type III 6.00-6 - 6 6 Type VII 40 x 14 40 14 - Three Part Name 19.5 x 6.75-8 19.5 6.75 8 Metric 380 x 150-5 380mm 150mm 5 MAKING OUR MARK ON RUNWAYS SINCE 1965. Contact Us +44 (0)1594 847 290 info@wattsaviation.co.uk Mead Lane, Lydney, Gloucestershire, GL15 5EL England Products & Services AIRLINE BUSINESS & CORPORATE GENERAL AVIATION HELICOPTER AIRCRAFT TUBES HARD TO FIND RETREADING AVIATION PARTS Copyright 2021 Watts Aviation. All Rights Reserved Website Policies | Privacy Policy Website Policies By using this website, you accept our use of 'cookies' and website policies. Read more Accept