The Crawler Innovations foam calculator was created to display all the foam options available for your application, arranged from softest to firmest. Rock Crawlers tend to perform better with the softer end of the foam spectrum in order to have forward bite while still controlling side wall flex. Trail Runners tend to perform better with the firmer foams that hold the shape of the tire at higher speeds but still give support to the tread as needed. Lil Nova 1.55, 1.7, & 1.9 - 4.0 all use the same outer, it's the closed cell inners that are different sizes. Lil Nova 4.25, 4.50, 4.75 all use the same outer, it's the closed cell inners that are different sizes. Double Deuce 5.0 & 5.25 use the same outer, it's the closed cell inners that are different sizes. Double Deuce 5.5 & 6.0 use the same outer, it's the closed cell inners that are different sizes. Essentially the foams are controlling the air pressure in the rc tire. The outer is controlling how quickly the tire responds, while the inner is supporting the overall tire and tracking of the rim.
Insightful Tips to Guide in Your Foam Quest
1. Compression ratios; desire more closed cell inner than conventional outer inside your tire = choose the larger size option. Desire more conventional outer than closed cell inner = choose the smaller size option. The inner controls the over all feel while the outer controls forward bite. Larger Closed Cell Inner = More control. Larger Conventional Outer = Softer overall tire with more forward bite.
2. Narrow foam options are designed for competition custom narrowed tires and rims.
3. Stepping up one outer density in the rear over the front is recommended because the weight of the rc vehicle shifts to the rear axle when climbing.
4. Dual Stage foam pair in the front, Single Stage foam pair in the rear, is a common general use set up. Dual Stage in the front helps control forward bite and cushion initial impact, while the Single Stage in the rear holds the tire up under any conditions.
5. Gray closed cell inners designed to handle weight 4-9 pounds. Black closed cell inners designed to handle weight 10 pounds and heavier.