I have dirtoval car with 17.5 and ae 2.25 transmission. I looking for roll out for240" center line. I have cw tires

most likely everything you can hang on it and you might still want more!

I run 88/50 with a 13.5 and an 2.6 tranny with 2.5" tires on an 140' runline.You could start there, but I imagine you will need more pinion.PRS makes them up to 65.

I had 1.95 transmission in it but that wood bbad or good .I see it take lot gear to make it fast.

I was 92\46 with a 10.5,170 ft driveline,cw rubber tires.
I would bet you'll go to an 80 spur 60 pinion with the 17.5

prolly like a 76-65

prolly like a 76-65

and wishing he had more!

I have rpm transmission . I can swicth drive gear assembly to 1.96 to 2.60. what one would work the best.

I have rpm transmission . I can swicth drive gear assembly to 1.96 to 2.60. what one would work the best.
1.96, but you have to swap the drive gear and the case, not just the drive gear.

that right .I will not have to use big pinion gear.what would be good roll out for 1.96

1.96 tranny and a 240' runline, again the anwer is everything you can hang! 76/65

who sell big pinion gear like that

PRS makes them up to 65.

who prs . web site

I found the web site thank for all ifo.

I ran 220' dirt track with 2.60 box and 17.5 at 60/76. Needed a bit more pinion.