You are comparing a car with lawn mower? Yes if you are not belted in, you can go though the windscreen at higher speeds that a stock lawnmower can go. Lets say you are going as fast as you can go on a lawn mower, you may hit a whole 14 mph on flat ground, I'll give you 16 mph going down hill, those are not road speeds. I think the term you were looking for is called INERTIA, maybe not. As far as bolting weight to the frame, you are putting more stress on the axle then if the weight is in the tires. When the weight is in the tires it is unsprung weight, if the weight is on the frame the axles now have more weight on them that is undo stress on bearings, bushings and tires just to name a few parts. As far as rust on the inside of the rims, your rims are painted, if you don't have any chips or scratches on the inside of your rim you should be OK. Now if you put calcium chloride in your tires, that stuff will eat the paint off the rims and you will get rust. But if you put tubes in your tires then put in calcium chloride in the tube you should be OK. You can put 50/50 water/anti-freeze in your tires and have no trouble with rust, anti-freeze has an anti-rust additive to stop rust just like it works in water cooled engines. The term WATER is used to described the fluid in general instead of saying anti-freeze and water 50/50 mix. When a engine manufacturer gives an in general description of the cooling of an engine, they use the word WATER to describe how the engine is cooled, like (air cooled)(water cooled) engines. Putting weight in tires is good for traction and ballast when you are on hills. Putting weight in your tires is the best way to add ballast and you can't get weight any closer to the ground then in your tires which are on the ground.....
Inertia is the word I was looking for, thanks for that!
Maybe the car was a bad way to explain it. Half fill a glass of water. Slide it across a table and stop it suddenly, what happens? The water will want to keep traveling in the same direction, but it cant. It will stop and then flow back in the opposite direction! It will flow back and forth until it settles.
But none of that matters. I doubt that much water will cause any kind of problem. I think I said that already!
When I read "fill the tires with water" I read it as, putting
water in the tires. Water and steel react causeing rust, you know that but you are right, rims are painted and any rust would take many years to cause dramas. Because I read it as water, all I meant was there are better alternatives like as you say, antifreeze etc. I only mentioned window washer fluid as that came to mind!
Yeah, weight on the frame probably isnt a great idea, was just a thought. You know, getting more weight down low, lowering centre of gravity!
Anyway, I wasnt saying to not do it, just pointing out a few things that Ive read over the years. Mainly with LT's, GT's and tractors. Hell, I had water in my little JDLT155 back in the day so, what ever!