rpmjem44
Active member
change to 275/60 R20 or 275/55 R20 is proper? Towing a 6,000 pound travel trailer on a 2009 Dodge Ram 1500 4x4 Hemi Crew Cab. Any suggestion will help. OE tire is 265/70 R17.
31.9' tire to 33' tires with 3.55 gear ratio a good idea?
- Thread starter rpmjem44
- Start date
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Roy M
Well-known member
Nope. You won't have enough power to get out of your own way and the brakes will be pushed beyonf their limits. The 33's will also require a body lift for adequate clearance. I bought a Ramcharger on 33's, hated them on the highway and couldn't tow my utility trailer with any kind of a load.
Arch Hoagland
Well-known member
In the old days we used to have two sets of rear tires for our car...snow tires and regular tires. Plus sand bags in the trunk.
Get the new ones and keep the old ones. Would take about an hour to swap them out.
Get the new ones and keep the old ones. Would take about an hour to swap them out.
OP
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rpmjem44
Active member
So it's best to keep it around 31' right?
Ernie n Tara
Well-known member
An inch makes about a 3% difference. I doubt you would even notice it.
Ernie
Ernie
OP
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rpmjem44
Active member
So it's doesn't really matter if I go 33' or is it better to stick to 31'
Gary RV_Wizard
Site Team
You need to figure the overall tire diameter for a given size. To get that data, use a tire size comparator such as https://tiresize.com/calculator/
Plugging in the 276/6R20 vs 265/70R17, I get about 4.4% increase (1.4") in diameter. Your speedometrer & odometer will be off by that 4.4% and acceleration decreased slightly because the final drive gear ratio also changes by that amount. Depending on what gearing you now have, it may be a modest difference or very noticeable. If the existing tires are near the edge of the acceptable gearing range, changing tire size could ush it over. If near the center of the optimal range, then it's probably not a big deal. This article helps determine how much effect to expect, but at the end of the day it is still subjective. Some drivers are very sensitive to speed and acceleration changes, while others simply don't notice.
https://www.onallcylinders.com/2015/07/30/tire-math-calculating-the-effects-of-tire-diameter-on-final-drive-ratio/
I have to ask why you want to change to 20"? Is it strictly for the look or are you trying to adjust performance in some way? Increasing tire diameter is generally a negative for hauling power, so you will want to weigh your priorities carefully.
Plugging in the 276/6R20 vs 265/70R17, I get about 4.4% increase (1.4") in diameter. Your speedometrer & odometer will be off by that 4.4% and acceleration decreased slightly because the final drive gear ratio also changes by that amount. Depending on what gearing you now have, it may be a modest difference or very noticeable. If the existing tires are near the edge of the acceptable gearing range, changing tire size could ush it over. If near the center of the optimal range, then it's probably not a big deal. This article helps determine how much effect to expect, but at the end of the day it is still subjective. Some drivers are very sensitive to speed and acceleration changes, while others simply don't notice.
https://www.onallcylinders.com/2015/07/30/tire-math-calculating-the-effects-of-tire-diameter-on-final-drive-ratio/
I have to ask why you want to change to 20"? Is it strictly for the look or are you trying to adjust performance in some way? Increasing tire diameter is generally a negative for hauling power, so you will want to weigh your priorities carefully.
OP
OP
rpmjem44
Active member
My gear ratio is 3.55 and yes I've check the chart and the OE revs/mile is 638 and changing it to 275/55r20 make it to 632 and the 275/60r20 make it to 612....so which is better?
OP
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rpmjem44
Active member
I bought my truck and it came with a 20 so basically I'm stuck with it unless I have to change everything
Roy M
Well-known member
In your original post you stated your OE wheels are 17" 3.55 is pretty stiff gearing with 20's.
OP
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rpmjem44
Active member
So what do you recommend? Change to 17 and go 275/55r20 for now until budget fit to overhaul to 17
Gary RV_Wizard
Site Team
I'm confused. You stated 17" was OEM, but you are stuck with 20"? Did a former owner switch to 20's? In that case, choose the tire that yields the closest overall diameter/circumference & rpms/mile to the original tires. That should put you near the optimum gearing. From what you stated, it sounds as though the 275/55 is very near the OEM size (632 vs 638 revs/mile). If it's really that close, no need to worry about 17" wheels in the future.
My 2009 Ram came with 275/60R20 tires. My son's 2018 Ram came with 17" rims but the tire ODs are pretty close. We considered trading wheels between the two trucks as my son wanted a more rugged tire tread for off road use. But we decided not to switch due to the tire OD difference effect on MPH readings. 3% sounds about right. That's not much and we may reconsider later.
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rpmjem44
Active member
Yeah the other owner changed it.... Yes the 55 is the closest I could get.... Look like I could only get the ko2
LT type and hoping they are good all around
LT type and hoping they are good all around
Broke Boater
Well-known member
Not really going to notice a difference with only a 1.5" increase tire size. Pretty common upgrade to that truck. The down side is 20's can get expensive vs 17's,,,gregg
OP
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rpmjem44
Active member
Yes... That I noticed lol.... Question.... What kind of LT tires handle the towing best and do I put 5 pounds of air in the rear more than the front when towing?
Gary RV_Wizard
Site Team
Not clear what you mean "What kind?". The right kind are ones with a sufficient load capacity to carry the truck and its payload. And you put enough air psi in to carry that load (per the load inflation table for that tire model & size).
The original tire & loading data placard should show the gross axle weights at max load. The tires selected for each axle need at least that much load rating. Divide the max axle load by the number of tires and add 10%-15% to allow for side-to-side imbalance. That's the minimum load capacity needed per tire. Use the tire brands inflation tables to determine the minimum psi needed for that load and then add 5 or so psi to that to give some extra working room to handle temperature and load changes.
The original tire & loading data placard should show the gross axle weights at max load. The tires selected for each axle need at least that much load rating. Divide the max axle load by the number of tires and add 10%-15% to allow for side-to-side imbalance. That's the minimum load capacity needed per tire. Use the tire brands inflation tables to determine the minimum psi needed for that load and then add 5 or so psi to that to give some extra working room to handle temperature and load changes.
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rpmjem44
Active member
Sorry... I meant what brand of tires.. I'll go with A/T since it's better in snow than the hwy kind
Gary RV_Wizard
Site Team
Same answer. Whatever brands are available that meet the qualifications.
I'd give serious consideration to Cooper, Hankook, Kumho, Bridgestone, and Continental.
Here are a number of choices in various price ranges:
https://www.discounttire.com/fitmentresult/tires/size/275-55-20?q=%3Aprice-asc&page=2
I'd give serious consideration to Cooper, Hankook, Kumho, Bridgestone, and Continental.
Here are a number of choices in various price ranges:
https://www.discounttire.com/fitmentresult/tires/size/275-55-20?q=%3Aprice-asc&page=2
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rpmjem44
Active member
Ok many thanks.... Bfgoodrich too?
