Cleaning and Stain Removal - black stains from road on white polyester dress

I got stains on the bottom of my beautiful white dress from the wet road, so I suppose oil and black rubber from tyres are the cause for these stains. I already handwashed it 40 degrees like it says on the label but could not get the stains out. The fabric is polyester and I was thinking of soaking the bottom in either citric acid solution or backing powder solution. Is that going to take the stains out or just ruining the fabric?

Try blotting stains with white rag and solvent cleaner like denatured alcohol or dry cleaning fluid. Wipe stain from outside toward middle to prevent spreading. Then soak and wash with heavy duty liquid laundry detergent.