Foam Tyres
Gluing Tyre Sidewalls
I’ve been given some tips by Andy Murray on the subject of putting glue on your foam tyres sidewalls to improve handling and reduce chunking.
Lower profile foam tyres give better handling, and while this is normally done by truing them down, it increases costs, as it means you either waste rubber by truing new tyres down to their “optimal” diameter, or run them with less than perfect handling at club races, then truing them down for bigger races.
But you can get a good deal of the effect by putting glue on the sidewalls, which makes them more rigid, giving a similar effect to the wheels being bigger, and the tyres being of a lower profile, even when they are box fresh. This reduces grip roll, and also helps avoid chunking.
He uses cyanoacrylate glue (AKA super glue). The best he found is made by Loctite, saying “brush on” in capitals in a blue box at the bottom of the label (he says others are too thick). That comes with a brush, which makes it easy to apply.
Apply the glue only to the outer sidewall.
With big tyres, he puts several layers, all the way up the sidewall of both the fronts and rears. This makes the car easier to drive, avoiding spin outs when turning hard, and eliminating grip roll (gluing the front and rear prevent different grip roll tyres, so do both).
Tyres with freshly glued up sidewalls will not chunk, so if you did it every run to stop peeling from the rim, it would stay unchunked. With the Loctite glue he recommends, gluing all four tyres takes less than a minute (it’s easier after the sidewalls are already hard). Just keep “topping it up”.
If you don’t do it every run, at least check for peeling (foam coming unglued from the wheel itself). That can give the car random tendencies, even if it doesn’t chunk during the run!