Hi everyone

So going to be getting new tires/rims for 71 442 street/strip. Currently running 245/60r14 and going to 275/60r15. My question is I'm running 3.73 gears and by going to a taller tire what would be a good gear to keep me in the same gearing that I have now?

 

If you want to maintain the same rpm with a taller tire then you will need more gear. 4.10 is you choice with OEM gears.

However you may like the lower cruise rpm with the taller tire. Try the car with the taller tires before swapping gears.

 

I agree. How do you know you have 3.73 gears. Did you install them or did someone when you bought the car say that is what was in there. DID you physically check and count teeth of ring and pinion?

Jim

 

Yes I did the gears. Actually purchased Moser complete 12 bolt. But yes I do need to drive it first just curious. 1/4 mile trap rpm was I believe around 5800 rpm and it still doesn't cruise that bad about 2800 rpm at 55mph.

 

I have never been able to drive an Olds at 55 mph. What's your secret?

 

Traffic

 

Your new tires are 9.5% taller than the old, so you need 9.5% more gear to maintain the same RPM. As Dave said, that would be a 4.10.

 

Thanks guys! Really appreciate it!