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DragBean · 12-12-2015, 01:54 PM

Toyota 4A-F and 7A-FE engines

According to this chart, my engines torque output is pretty much flat after 2500 rpms.

Since I don't travel really less than 60 on the highway I'm guessing this means that I should aim for a tire size that gives me 2500 rpms at 60 mph? And then any speed beyond that is good as far as torque is concerned.

The one issue I have is that the torque output is at full load... We're hardly ever driving there. However, I guess this makes sure that all the parts can handle the increased torque load from bigger tires.

Anyways my car has no tachometer on it, so I looked up my gear ratio for the three gear A131 Auto Tranny to deduce my rpms.

1993-1997 Toyota Corolla transmissions and axles

Right now I'm going 3330 RPMS at 60 mph with my worn tires at 21 3/8 OD and with new tires at 22.5" OD that are the same it would be 3180 RPMS. Still high.

So if I were going to go 2500 rpms at 60 mph, that would be a 28.22 OD on the tire.

I think I'll go for 2800 rpms just to be on the safe side, so that yields a 25" OD.

That doesn't sound too drastic. A 10% change from stock conditions, 15% change from my current worn tire conditions.

12-12-2015, 01:54 PM	#13 (permalink)
DragBean PizzaRimBoy Join Date: Dec 2015 Location: SoCal Posts: 72 Thanks: 2 Thanked 15 Times in 7 Posts	Doing the Math Toyota 4A-F and 7A-FE engines According to this chart, my engines torque output is pretty much flat after 2500 rpms. Since I don't travel really less than 60 on the highway I'm guessing this means that I should aim for a tire size that gives me 2500 rpms at 60 mph? And then any speed beyond that is good as far as torque is concerned. The one issue I have is that the torque output is at full load... We're hardly ever driving there. However, I guess this makes sure that all the parts can handle the increased torque load from bigger tires. Anyways my car has no tachometer on it, so I looked up my gear ratio for the three gear A131 Auto Tranny to deduce my rpms. 1993-1997 Toyota Corolla transmissions and axles Right now I'm going 3330 RPMS at 60 mph with my worn tires at 21 3/8 OD and with new tires at 22.5" OD that are the same it would be 3180 RPMS. Still high. So if I were going to go 2500 rpms at 60 mph, that would be a 28.22 OD on the tire. I think I'll go for 2800 rpms just to be on the safe side, so that yields a 25" OD. That doesn't sound too drastic. A 10% change from stock conditions, 15% change from my current worn tire conditions.