View Full Version : Mounting ContactRC foams to offroad rims

15-07-2014, 06:42 PM
A number of fellow racers have asked me how I mount foam tyres to my offroad rims, they say this is what's putting them off trying foams.

It's really simple and in a lots of ways easier than mounting mini pins/spikes; you only have to do it once for many many weeks of racing, no balancing issues, no trimming of beads/ensuring the bead sits correctly, not having thin superglue run down your arm etc.

Here is what you need:

ContactRC JY45 front and JY35 rear foam donuts.
An old set of front and rear wheels.
An old stub axle with 12mm hex fitment.
A drill (cordless is best because it runs slower).
A sturdy stanley knife.
Curved lexan scissors.
Loctite powerflex superglue gel.

The process:

1. Using the lexan scissors trim the inner ribs off the wheels (scissors curved edge away from wheel) but leave the outer dish intact. You don't have to be neat, just take off as much as you can. No need to break out the dremel.

2. Decide whether to mount full, slim or 'somewhere inbetween' front width. I prefer slim as it gives the most even steering through the corner, go wider for more turn-in. Trim the inside edge of the front wheels accordingly.

3. Clean the rims and inside surface of the donuts with motor spray and leave to dry.

4. You will notice a slight kink to the donut's profile on one side, this is from the 'stamp' cutting process when they are made. This is the edge you want to lose so stretch the other squarer profile side over the rim first until it's flush with the outer dish and has equal overhang the other side.

5. Mount the axle in your drill and fix the wheel to it. Spin it up and gently slice the excess tyre a bit at a time until what remains is approximately the width of the rim, a couple of mm is here nor there.

6. Use the loctite power flex glue to stick the outer and inner edge of the tyre to the rim. Check after the first few runs and glue again where necessary. I tried contact adhesive but is went everwhere and needed re-gluing weekly.

There's absolutely no need to true the tyres (these are buggies not high precision LMP racers!) the supplied diameter is perfect for buggies. The profile will start to take shape after a couple of rounds, keep an eye out for uneven wear and adjust camber accordingly. You want the profile to resemble that of a mini pin it will take a couple of weeks to get there but will work fine until then. Additive helps speed this up.

Mount the wheels to the car, set ride height, apply an additive of your choice and go race!

15-07-2014, 07:01 PM
We use these at our club and have done for over a year, I simply slide the donut over the rim and trim but leave the inner beads on the wheels as it gives the rim more rigidity especially if you crash a lot :o likewise I then glue and true them on the carpet when racing :thumbsup: they last for ages providing you don't chunk them but just keep an eye on any splits that start to develop.

Mike Nash
15-07-2014, 07:49 PM
I did mine with double sided tape have run on them for the last 2 weeks and had no problems. I did cut the ribs of the wheels
To get the foams on just use hot soppy water once dried they stick like s..t to a blanket.

I then trued them with the drill

15-07-2014, 07:55 PM
Thanks Lee and Mike for the alternative methods. There's no one way of doing this so keep the options coming and people can choose the method they feel most comfortable with.

Lee, out of interest, how did your club find the performance of foams in general?

15-07-2014, 09:01 PM
A word of warning does need to be made about the testing of Foams. Never have your Wheels off of the ground & have your speedo set to full turbo. I did this with the first set of foams I bought, I had my Speed Passion Reventon Pro set with full Hyperboost on had the car supported at the front & rear all wheels off the ground & hit Full Throttle, the rear tyres promptly exploded as did my rear end.


15-07-2014, 09:21 PM
Thanks Lee and Mike for the alternative methods. There's no one way of doing this so keep the options coming and people can choose the method they feel most comfortable with.

Lee, out of interest, how did your club find the performance of foams in general?

In terms of speed a good second to a second and a half a lap faster.

15-07-2014, 09:28 PM
And I've been having fun with ego-stick and thinners... old school style....:woot:

15-07-2014, 09:28 PM
that was evo* stick. not ego stick.

15-07-2014, 10:00 PM
I can't even imagine how that must smell!

15-07-2014, 11:04 PM

24-07-2014, 11:05 AM
Guys I Have bought some concepts front and rear foams, I have a set off wheels, guys at the club told me to cut out the ribs, i've done this but only the internal ribs, people are saying do the external some say dont.... HELP in 2 minds what to do

24-07-2014, 12:12 PM
I leave the external rib on, mainly as it is easier to locate the foam on the rim. I cut the rest of the ribs off.

I use double sided carpet tape on the rim, if you blast the inside of the foam and the tape, the tyre will slide over the tape and give you enough time to 'adjust', I never trim down the foam until on the rim, I also trim as the tyre won't be round when fitted and round the shoulders. Aslo, when you look at the tyre, there is normally a shinny (sealed) side and an open side.... I put the sealed side outwards.

09-08-2014, 08:19 AM
Hi! Thanks for the useful tips!!
One question: I mounted these Contact foams on Schumacher black 2wd front and back wheels.
I found that with a little squeezing they fit fine without any trimming.
Is this correct? Anyone having done the same?
Thanks for helping! ;)