Let me know if there is a similar thread already, my search didn't turn up anything.
I currently run 295/70 R18 (34.5") tires on my truck. With the 4 speed transmission and 4.88 diff gears, the speedometer read very accurate! Now that the winter is around the corner, I am shopping for winter tires. Apparently there are no 34+" tires available for 18" rims. I do not consider the AT tires with snowflake rating to be a true winter tire so those don't count.
The most common size available is 275/65 R18 (32"). A slightly rarer size is 275/70 R18 (33.2"). I can get a killer deal on the 32" tires mounted on wheels from a fellow mudder or spend a bit more and get 33" tires mounted on a spare set of wheels that I already have.
My concerns are that 32" tires would be too small due to diff gearing and will cause the cruising RPM at 80mph to be close to 3500 RPMs. Engine speed with 33" tires would still be slightly higher than what I have with 34.5" but perhaps it will be manageable.
What do you guys think?
EDIT on 10/8/2021
Looks like I am over thinking this (not a surprise really ). The RPM difference at 80 MPH is not really that big between 32 and 34. So perhaps it would make sense to decide based on price. Here's a quick comparison via an online calculator:
source: Gear Ratio Comparison Tool - Compare Axle, Transmission Combinations - https://www.dieselhub.com/tech/ratio-tool.html
If this calculator is accurate, it would mean only a couple of hundred RPMs separate the 34" and 32" tires. I am sure I can live with that!
I currently run 295/70 R18 (34.5") tires on my truck. With the 4 speed transmission and 4.88 diff gears, the speedometer read very accurate! Now that the winter is around the corner, I am shopping for winter tires. Apparently there are no 34+" tires available for 18" rims. I do not consider the AT tires with snowflake rating to be a true winter tire so those don't count.
The most common size available is 275/65 R18 (32"). A slightly rarer size is 275/70 R18 (33.2"). I can get a killer deal on the 32" tires mounted on wheels from a fellow mudder or spend a bit more and get 33" tires mounted on a spare set of wheels that I already have.
My concerns are that 32" tires would be too small due to diff gearing and will cause the cruising RPM at 80mph to be close to 3500 RPMs. Engine speed with 33" tires would still be slightly higher than what I have with 34.5" but perhaps it will be manageable.
What do you guys think?
EDIT on 10/8/2021
Looks like I am over thinking this (not a surprise really ). The RPM difference at 80 MPH is not really that big between 32 and 34. So perhaps it would make sense to decide based on price. Here's a quick comparison via an online calculator:
source: Gear Ratio Comparison Tool - Compare Axle, Transmission Combinations - https://www.dieselhub.com/tech/ratio-tool.html
If this calculator is accurate, it would mean only a couple of hundred RPMs separate the 34" and 32" tires. I am sure I can live with that!
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