Will 13" wheels bolt pattern 4x100 fit on my 3rd gen?

Maybe, the stock wheels are 13" in some markets so might clear the brakes. At least the PCD is correct. It really all depends on the width and offset though. The stock wheels were either 13x6 +37 or 14x6.5 +37.

This is for USDM models...13 inch wheels will fit on your 3rd gen if you have an S model (dual carbs). They will not fit if your 3rd gen is an Si (fuel injected). The S model has smaller front brake rotors, and actually came with 13 inch wheels. The smallest you can mount onto an Si model is 14 inch.

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1991 Prelude Si ALB 4WS
2017 Ram Rebel

Ok thanks.

Now I'm confused. Here in Aus we (mostly) only got the 2.0Si (injected not carb) and it came standard with 13's on it. Did this model have the smaller brakes too?

Sorry, I really can't speak for AUDM models and how they may have been equipped. I only know about USDM models and what they came with. All carb'd 3rd gens in the US came with 13 inch wheels and had smaller front brakes, and all fuel injected models in the US came with 14 inch wheels and had bigger front brakes. The rear brakes were the same whether carb'd or fuel injected.

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1991 Prelude Si ALB 4WS
2017 Ram Rebel