conversion from mm to 1/25 scale question

[V8tiger]

I find files for wheels but have no Idea how to scale them in my slicer for 1/25 scale... what do you guys do... I don't want to be just guessing. 

[stitchdup]

I use this site to find out what to rescale with. http://www.scalemodelersworld.com/online-scale-converter-tool.html

I also download free files of wheels the size i want so i can use them to check the sizes before printing. sometimes you do just have to guess though

[iamsuperdan]

https://www.digitaltaxidermy.co.uk/scale-converters

I use this link for conversions.

[Force]

You don't have to guess, it's just basic mathematics.
1:25th scale, the obect is 25 times smaller that the real object.
1:24th scale, the object is 24 times smaller that the real obejct.
Inch to mm conversion, 1 inch is 25.4 mm so 1 inch in the real world is slightly over 1 mm in 1:25th scale, 1.016 mm to be exact.
So if you have a wheel that's 19 inches in the real world, that's 19 times 25.4 = 482.6 mm, divide that with 25 and you will get 19.304 mm.