Hawkeye Downs Speedway in Cedar Rapids Iowa is celebrating their 100th anniversary of operation this year. We were fortunate to locate an open wheel racecar that competed in the first race held at the track in 1925. We are even more fortunate that the current owners have loaned the car long term to Hawkeye Downs to display it. I could use your help in determining what tires this racecar needs. The rims are 23" diameter Dayton wires and their width is 3". A local Model T owner said we need tires like the ones used on a Model T truck with a 23" split rim. He said we could use a 30 x 3-1/2 (30" outside diameter x 3-1/2" tall sidewall) or a 31 x 4 (31 outside diameter x 4" tall sidewall). Can any of you experts verify that he is correct and that these two tires sizes are what I should be looking for? And based on the photos I have attached, do I need tires for a split rim and not for a clincher rim?
They appear to be 23" rims Those rims are "straight side" rims. Clincher tires will not work on these rims. You need "Straight side " tires. There aren't a lot of choices in 23" straight side tires. Most would look to big on a car like this. I checked around and probably the best choice size wise is, Lucas Olympic tread 31 x 4 (440 x 23). All the other choices are on the bigger side, and I think they would look out of place on a car that small. I've worked on quite a few early race cars Here's one of mine
Thanks for the info Pete. When you say 'straight side' tires are these also called 'split rim' tires? I just want to make sure I am looking for the correct tires. My best case scenario is to find a used set of tires. With the condition of the racecar new tires would look out of place.
Your rims are “lock ring” type, often referred to incorrectly as “split rim”. Straight side tires are basically the same bead type we think of as normal in today’s tire design. In the early years, clincher type tires were quite common, and were also the type used on Model T Ford. Clincher and straight side tires are not interchangeable, as the rims are very different. For about the last 60 years, the 30” x 3-1/2” clincher tire offering has been known as “oversize”, and are actually 31” x 4” dimensions. Pete’s tire suggestion is likely your best tire option. I don’t suspect you will find any used tires, this size and bead type is fairly uncommon
This appears to be what was suggested by @Pete Eastwood above: https://lucasclassictires.com/tires/31x4440-23-lucas-olympic-tread-blackwall/
Model T with Simplex brand wire wheels and 30” x 3-1/2” clinchers. Note that these tires predate the “consolidation” of tire sizes, so are truly 30” x 3-1/2”, modern tires are “oversize” so actually 31” x 4”
This is a British company but there’s some good detail on the different tyres as the guys above have stated. https://www.longstonetyres.co.uk/vintage-tyres.html
The Jalopy Journal
