How do you replicate bulged tires on a modern cargo truck (plastic kit tires not rubber)?

Apart from reducing pressure on tires when a vehicle is going cross-country in soft terrain (or have I got that reversed?) the bulged tires on models, is, IMO, a bit of a myth. The best example of this was in the now infamous(?) debate over the buldged tires on DML's M2 H/T. No evidence exists whatsoever for this on the M2. There are modern vehicles which have a tire pressure controller (the big Russian Maz vehicles have this) but I haven't seen much evidence to suggest that low tiree-pressure is little more than a modeler's 'aesthetic'... Any 'operators' out there who can shed more light on this?

As to reproducing bulges - it would involve a virtual rebuild of the tire (and then multiply it by the number of tires on a vehicle) making sure each was identical. That'd be a nice project for those long winter evenings - imagine on an Oshkosh Tank transporter...Eeeek!

In a perfect world most vehicles a properly inflated tire will not show any bulging.

The problem is that this world is rarely perfect. Tires will loose pressure more often than not on combat vehicles, even with self inflating systems.

To be more realistic I prefer the bulged tire look. Gives it more character.

I bet that I could walk out into the vehicle park and at least half the tires would be under inflated with bulges.


cheers from the sandbox

Not getting into the debate whether it is realistic on not.

To replicate it w/plastic tires is pretty easy. Heat the portion to be bulged gently over a flame until it softens. Press it firmly down onto a flat surface and the plastic will bulge at the sides as you compress it.

For resin or rubber tires, you have to cut a flat spot on the tire, then build up the bulged sidewall with putty.

Evan,you can glue a small section of plastic to the inside of the tire(for rubber tires) and then glue the other to the wheel,you have to be careful and measure the plastic( i use a piece of sprue)to make sure the"bulged"part isn't too apparent,as for plastic tires,I have a small cheap travel size iron I keep to use for this very purpose,I just turn it upside down and press the tires on the surace of the iron until they look right.Use a piece of aluminum foil
to keep the surface of the iron from ending up with melted plastic all over it,I use this for most of aircraft models.I seldom worry about weighted tires on my AFV's,or autos.
Hope this might help somewhat.
Bob

Hi

If my memory serves me correctly hasn't the actual construction, the internal material etc. of a tyre changed considerably over the years. Something about Radial and cross-ply tires.

I'm not sure if this has any relevance on if a tyre would be bulged or not but certainly it would be better to reference a tyre image, or actual, made in the time period the vehicle comes from to see if there is a possibility that this effect did occur and how it looked.

I know I had a car once that despite its front tyres always being correctly inflated to the recommended pressure bulged slightly and looked under inflated all the time.

I'd actually say there is a difference in appearance between a bulged tyre, which to me is a correctly inflated tyre "bulging" under the weight of the vehicle its on and one that is under inflated and losing air.

But in modelling terms I'd say the techniques offered above to represent it would be acceptable for either circumstance.

Alan

As Rick pointed out, more often than not in a vehicle park or in a convoy, some tires will exhibit less than ideal pressure potentially creating a slight bulge. Plus the terrain being driven over, especially in vehicles with 6 or 8 wheels, will exhert different pressures on different tires, causing some to look normal and some to bulge a little. That said, one way I found how to duplicate his was in building Tamiya's HMMWV M1025. I used Bob's method described above and here's a bit more detail:

This works for plastic or resin wheel rims and standard hollow-rubber type tires that stretch to fit over the wheel/rim. If you glue a small block of plastic to the rim where the bottom of the tire will be, slip the tire over the rim after putting a small dab of CA glue at the bottom of the block, hold the rubber tire against the glue spot on the block in the inside until it sets and voila, you have a bulged tire. The size of the block (ie the distance from the rim to the bottom of the small block) will determine how much of a bulge you get. A little CA glue around the rim seal of the tire, and you're set.

The discussion around realism really comes to a head when the effect is seemingly overdone and the tire looks like it's almost flat. A little is okay, too much is not realistic IMO. Unless you're modelling a damaged vehicle or a repair candidate, this generally wouldn't appear to be realistic. I dodn't do this all the time, but sometimes it seems appropriate.


It looks like this when complete:






(other) Bob

Yes !

One of the most important things that was overlooked by both sides during the 'battle of the bulge' debate.

I have an old International Harvester farm tractor similar to this one below.



The tires construction is designed to run 'flat' in case you puncture them while working the field, much like those tires of the vehicle that spawned that whole battle.

I run those huge, sixty inch tires on the tractor with twelve pounds in each tire and they don't show any 'bulging' at all, it has nothing to do with air pressure and everything to do with tire construction.

Yeah, Im not getting into the debate either, especially since Ive seen tires bulging on vehicles like the LAV25, etc.


Just to add to Gino's way, rather then using a flame and risking a fire, you can also try dipping the tire in boiling water and then pressing it on a flat surface like a counter top or such. This way is alittle slower as you'll probably have to heat the tire a few times and press it to get the desired effect, but also, since your working slower, it will be easier to make multiple bulging tires match and make them even.