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Posted

 

Thanks man.

 

Front 2.5" level and 2.5" block in the rear. 295's are just a tad narrower than the 305's. The difference is minimal and barely noticeable, but enough to prevent me from rubbing. I do still rub, but only at full lock in reverse. The 305's would've probably required trimming.

Thanks for the description. With the 2.5" up front and 2.5" block in the back, what is the truck stance? High in front, back or level? Thanks!

Posted

Thanks for the description. With the 2.5" up front and 2.5" block in the back, what is the truck stance? High in front, back or level? Thanks!

 

The rear has somewhere between .5-1" of rake. With the 2.5" level up front, the truck measured completely level, but looked nose high. With the larger block in the rear, the truck has slight rake, but actually looks level.

Posted

Since many people are looking helpful today. I got a question I'm looking at bigger tires and not by much maybe an inch but the weight is an additional 3 lbs. How would that much unsprung weight affect everything?

 

sent from Florida beech

Posted

Since many people are looking helpful today. I got a question I'm looking at bigger tires and not by much maybe an inch but the weight is an additional 3 lbs. How would that much unsprung weight affect everything?

 

sent from Florida beech

 

I wouldnt worry about 3lbs. I feel like you wont notice that small a difference.

Posted

 

I wouldnt worry about 3lbs. I feel like you wont notice that small a difference.

OK thank you

 

sent from Florida beech

Posted

Since many people are looking helpful today. I got a question I'm looking at bigger tires and not by much maybe an inch but the weight is an additional 3 lbs. How would that much unsprung weight affect everything?

 

sent from Florida beech

Going to see a minor hit in MPG depending on how much city driving versus highway driving you do. The unsprung weight is negligible in regards to steering and suspension function these would be more affected by the design and construction of the tire itself. The torque required to get the tires moving is governed by the equation 1/2mass x radius squared so the increase in diameter plays a bigger role in the affect on performance in 2 ways. It causes the engine to operate in a lower RPM for the same speed reducing the available torque from the motor and the additional diameter requires more torque to turn, it's a double whammy and you pay the price in efficiency or MPG's.

Posted

Going to see a minor hit in MPG depending on how much city driving versus highway driving you do. The unsprung weight is negligible in regards to steering and suspension function these would be more affected by the design and construction of the tire itself. The torque required to get the tires moving is governed by the equation 1/2mass x radius squared so the increase in diameter plays a bigger role in the affect on performance in 2 ways. It causes the engine to operate in a lower RPM for the same speed reducing the available torque from the motor and the additional diameter requires more torque to turn, it's a double whammy and you pay the price in efficiency or MPG's.

It's pretty much exclusively city driving. Boat is in city everything is here. The tires are only like 1.2 or 1.3 inches higher I just wanted something more aggressive if the downside wasn't too much. It's a cooper at. Not anything crazy massive off road wise. Just slightly more aggressive and only slightly bigger

 

sent from Florida beech

Posted

I went from the factory 20 inch wheels with the goodyear 275 55 Sra's at 80 lbs per corner to 18 inch wheels with 285 65 toyos at 82 lbs per corner and lost about 1.5 mpg on average.

Posted

I went from the factory 20 inch wheels with the goodyear 275 55 Sra's at 80 lbs per corner to 18 inch wheels with 285 65 toyos at 82 lbs per corner and lost about 1.5 mpg on average.

 

Wow from 2lb increase!

  • Like 1
Posted

 

Wow from 2lb increase!

It's a combination of the weight and the additional diameter. And there's more to it than just overall weight alone. Even though they only differed by 2lbs total, the weight distribution changed. the 18 inch wheels are lighter than the 20's and the 10 ply tires are heavier than the 4 ply SRA's so more of the rotating mass moved further away from the center and since torque is mass x distance this significantly increased the torque requirement even though the overall weight did not change significantly. The easiest way to think about it is holding a hammer. It's like holding the hammer by the head versus holding it at the end of the handle, weighs the same but takes way more strength to hold it by the handle.

Posted (edited)

It's a combination of the weight and the additional diameter. And there's more to it than just overall weight alone. Even though they only differed by 2lbs total, the weight distribution changed. the 18 inch wheels are lighter than the 20's and the 10 ply tires are heavier than the 4 ply SRA's so more of the rotating mass moved further away from the center and since torque is mass x distance this significantly increased the torque requirement even though the overall weight did not change significantly. The easiest way to think about it is holding a hammer. It's like holding the hammer by the head versus holding it at the end of the handle, weighs the same but takes way more strength to hold it by the handle.

 

Makes sense, guess I didnt think through that all the way. I was thinking if I could keep weight similar Id be okay, but Im going to get dinged too then going from 20s to 17s.

Edited by jrob56
Posted

Tread pattern also has an impact as rolling resistance increases with greater tread void and construction. Comparing anything to the SRA's (which are designed as a highway tire) will likely show a decrease in mileage.

Posted

Tread pattern also has an impact as rolling resistance increases with greater tread void and construction. Comparing anything to the SRA's (which are designed as a highway tire) will likely show a decrease in mileage.

I'm not worried about mpg. I'm worried about causing damage to my truck since it's a slightly larger tire than stock

 

sent from Florida beech

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