plywood
We have a curved wall framed with steel studs 16"o.c. that will be finished with hardwood planks (running vertically on the wall).
For the hardwoods substrate, they recommended plywood and normal plywood does not conform to the curve. Our lumber supplier suggested snakeply (wiggle wood, a.k.a flexible plywood) which conforms to the wall easily, but it is still very soft in between the studs.
Is there a way to stiffen up the snakeply?
I think the best method is to use an anti slip tape / strip / paint
Tape
Strip
Paint
They are ordered form easiest to hardest.
The strips will be the easiest because you just stick them on. You will obviously stick them on the length where your tires will be going and not sideways (because that would be pointless). The strips are more durable, but don't be deceived by the stick on ones once they are stuck.. they are STUCK! The best, but most work is painting the whole ramp.
Preparation.
Needs to be a dry day for sticking on or painting. You need to clean the surface with paper towels - after you wiped the dirt away and the surface you want to stick/paint is dry you will use more paper towels and cheap alcohol (methanol, spirits, etc) - Using the alcohol cleans the surface and removes oil (so don't touch it after you wiped it). Clean it almost like waxing (several times the same spot), this will guarantee your surface is dirt free and guarantees best adhesion for years and years of life.
The strips you can just put down - but you need some cordless drill or elbow grease to get those screws in. Make sure they are flush (level with the strip) or you risk slashing your tires.
Here are some links
http://www.vubasupplies.co.uk/anti-slip-surfaces.html
There are a number of methods to apply large decals and stickers to surfaces while avoiding bubbles and wrinkles.
Most professionals prefer a wet method. Clean the surface first. Then coat the surface, or the adhesive side of the sticker, or both, with slightly soapy water. Then lay it down slowly and use a squeegee while laying it down. The soapy water enables you to lift it back up a little if you introduce a bubble or wrinkle. The squeegee squeezes the soapy water out from under it.
A number of videos show the process, search for "decal wet method" or "vinyl wet application" for some. I think http://www.youtube.com/watch?v=RSVk0C_NLpc is probably most applicable to your specific usage.
Also, ask the shop you're buying the decal from for their suggestions.
Note that unless you've purchased high quality plywood, and spent some time sanding, sealing, and filling, it's probably not going to be a very smooth surface anyway, and a high quality vinyl decal will look pretty lumpy on it. Consider getting a better surface, or seeing if you can have a matte vinyl decal made, which reduces the glossy reflections which will show surface defects very clearly.
Best Answer
Laminating a second layer of the same product should stiffen it substantially. Once the first layer is positioned the way you want, spread several beads of construction adhesive across the face of it and conform a second layer over the first. Tack in place with brads using a nailgun to hold it in place until the adhesive sets.
Note: These flexible plywoods come in a variety of thicknesses. It is likely that the thicker ones will be somewhat stiffer than the thin ones. I realize that even the thick ones may not be rigid enough for your application.