wildebill308 Report post Posted May 17, 2019 Saw a trailer with a add on it for a wheel conversion to 19.5. I know they do the 19.5 conversion on Dodge trucks but hadn't seen it on tow behind trailers. http://www.boarwheel.com/ Might be a good idea if you are near your upper weight on your current tires and rims. Bill Share this post Link to post Share on other sites
richard5933 Report post Posted May 17, 2019 Just have to be careful to still take into account load capacity of axle and the other suspension components. Sometimes putting higher capacity wheels/tires doesn't matter since the axle and springs will still be overloaded. Share this post Link to post Share on other sites
desertdeals69 Report post Posted May 17, 2019 If the diameter is larger the brakes have to be improved. Share this post Link to post Share on other sites
wildebill308 Report post Posted May 17, 2019 9 hours ago, richard5933 said: Just have to be careful to still take into account load capacity of axle and the other suspension components. Sometimes putting higher capacity wheels/tires doesn't matter since the axle and springs will still be overloaded. I re read what I posted and funny, I never said you could increase the load rating. Nor did I say it would be ok to do. What this post is about (pay close attention) is increasing the safety margin from most stock trailer tires. While a lot of people are going to the 16"LT tire this upgrade would improve the safety margin further. 8 hours ago, desertdeals69 said: If the diameter is larger the brakes have to be improved. Lets see, going from a 235/85R 16 to a 225/70R 19.5 would increase your diameter 0.2" I really don't see a problem. Bill Share this post Link to post Share on other sites
richard5933 Report post Posted May 17, 2019 8 hours ago, WILDEBILL308 said: I re read what I posted and funny, I never said you could increase the load rating. Nor did I say it would be ok to do. What this post is about (pay close attention) is increasing the safety margin from most stock trailer tires. While a lot of people are going to the 16"LT tire this upgrade would improve the safety margin further. My reply was written because you mentioned being near the upper weight limit on the tires. I wasn't aiming the comment directly at you, but more so at anyone that might be reading this thread and mistakenly think that we're talking about the overall load limit for the vehicle. I've read many threads on other sites where people seemed to think that bigger tires would increase the load capacity of a vehicle. Sorry if I came across wrong. Share this post Link to post Share on other sites
jleamont Report post Posted May 17, 2019 The overall Diameter isn't enough to make an impact. The rolling resistance of all that weight I would think could increase the stopping distance, how much, I do not know. Plus those tires will send more road vibrations into the trailer, depending on the manufacture of the trailer id bet it will break stuff, keep in mind, in most cases they do not have shock absorbers, so there is nothing to help dampen the effects. I have seen many trailer frames and suspensions crack, I would imagine this would accelerate the condition. I get the concept but if they would just obey the speed ratings on those stock tires 95% of their "blowouts" would be eliminated. Every trailer I have owned over the years came with low budget chinese tires, I wore them off and not ONE failure. You have to properly maintain and operate equipment for it to pay you back. Share this post Link to post Share on other sites
desertdeals69 Report post Posted May 17, 2019 As far as brake requirements It does make a difference. I had a Spartan diesel pusher chassis that I converted 19.5 wheels to 22.5 wheels to improve the ride. Before I did it I talked with 2 engineers at Spartan and was told it wouldn't be a problem with the brakes because I was not increasing the weight. I went ahead and did it and the brake efficiency decreased. Did some thinking and figured out that the increase in radius changed the leverage on the brakes. I then went and changed the steel springs to air ride and larger axles with air brakes and solve the problem. Share this post Link to post Share on other sites
tireman9 Report post Posted May 17, 2019 13 hours ago, desertdeals69 said: If the diameter is larger the brakes have to be improved. Not sure if I understand your comment. Are you saying that if you change (increase) wheel diameter you will need to also change the brake system? or are you saying that an increase in wheel diameter will result in improved brake performance due to better cooling? Share this post Link to post Share on other sites
tireman9 Report post Posted May 17, 2019 12 hours ago, WILDEBILL308 said: I re read what I posted and funny, I never said you could increase the load rating. Nor did I say it would be ok to do. What this post is about (pay close attention) is increasing the safety margin from most stock trailer tires. While a lot of people are going to the 16"LT tire this upgrade would improve the safety margin further. Let's see, going from a 235/85R 16 to a 225/70R 19.5 would increase your diameter 0.2" I really don't see a problem. Bill 1 Let's see An ST235/85R16 LR-E is rated 3,640# while a commercial truck 225/70R19.5 LR-E is good for 3,195# @80 psi and the LR-F at 95 is rated 3,640 But LR-G @110 psi is rated for 3,970# This post is about trailer application. If considering the change IMO the brake performance would be a little better just from the increased clearance and cooling. I saw this in my race car. BUT if you are looking for more load capacity "Reserve Load" then yes just be sure to get the LR-G and run 110psi. Don't forget all you are gaining is tire reserve load and not more load capacity for the RV. Share this post Link to post Share on other sites
desertdeals69 Report post Posted May 17, 2019 5 hours ago, tireman9 said: Not sure if I understand your comment. Are you saying that if you change (increase) wheel diameter you will need to also change the brake system? or are you saying that an increase in wheel diameter will result in improved brake performance due to better cooling? Roger, If you think about it this way, the longer the radius the more rotational leverage you have on the brake mechanism. Like pulling a nail with a longer handle on the hammer. I proved it when I did my conversion, even arguing with the chassis engineers. They finally agreed with me. My original disc brakes were air over hydraulic were too weak thats when I went to air suspension and air brakes on bigger axles. Share this post Link to post Share on other sites
jleamont Report post Posted May 17, 2019 43 minutes ago, desertdeals69 said: If you think about it this way, the longer the radius the more rotational leverage you have on the brake mechanism Very common practice to upgrade brakes on lifted trucks and high performance cars that were not originally a high performance car. Lifted trucks its critical, when I lifted our last jeep, it increased its stopping distance due to the larger tires. I up graded the front brakes to a larger rotor with more surface, dual piston calipers and installed disc brakes on the rear (drum from the factory). Share this post Link to post Share on other sites
richard5933 Report post Posted May 17, 2019 Even if the diameter didn't change, wouldn't the larger wheels/tires increase the mass being rotated? Which would require more stopping power? Share this post Link to post Share on other sites
wildebill308 Report post Posted May 18, 2019 3 hours ago, richard5933 said: Even if the diameter didn't change, wouldn't the larger wheels/tires increase the mass being rotated? Which would require more stopping power? The weight might be slightly higher but in the example I was talking about you only have a increase in diameter of 0.2". That would be less than the difference between used and new. Without a scale I don't know how much heavier the rims are. The confusion I see is people assuming because it is a 19.5 it is bigger than a 16". While the rim is, the diameter of the package is the same. Bill Share this post Link to post Share on other sites
jleamont Report post Posted May 18, 2019 (edited) 14 hours ago, richard5933 said: Even if the diameter didn't change, wouldn't the larger wheels/tires increase the mass being rotated? Which would require more stopping power? Absolutely! Let me elaborate, heavier wheels and tires will increase rotational mass. We do not know if these would actually increase rotational mass, we are assuming the 19.5 would be heavier. Depending on the wheel design and materials, it might not be. Edited May 18, 2019 by jleamont Elaborating previous response Share this post Link to post Share on other sites
wildebill308 Report post Posted May 18, 2019 20 hours ago, tireman9 said: Let's see An ST235/85R16 LR-E is rated 3,640# while a commercial truck 225/70R19.5 LR-E is good for 3,195# @80 psi and the LR-F at 95 is rated 3,640 But LR-G @110 psi is rated for 3,970# Yes lets see, Why would someone upgrade to a 19.5 and run an inferior tire to the original? Can you explain that to me? I am only going to use the current Michelin chart. I don't know where you got your information on the 225/70R19.5 G but it is completely wrong. In a single application at 65 psi it can handle 5510#. (By the way 65psi is the lowest recommended preshure for this tire) but at 110 psi it is rated for 7940#. https://www.michelintruck.com/reference-materials/manuals-bulletins-and-warranties/load-and-inflation-tables/#/ I also wonder why you are advocating running the max sidewall preshure? I would think it would be a better practise to weigh the trailer (all wheel locations or by axel) and adjust the preshure accordingly. Bill Share this post Link to post Share on other sites
bm02tj Report post Posted May 18, 2019 19 hours ago, WILDEBILL308 said: Yes lets see, Why would someone upgrade to a 19.5 and run an inferior tire to the original? Can you explain that to me? I am only going to use the current Michelin chart. I don't know where you got your information on the 225/70R19.5 G but it is completely wrong. In a single application at 65 psi it can handle 5510#. (By the way 65psi is the lowest recommended preshure for this tire) but at 110 psi it is rated for 7940#. https://www.michelintruck.com/reference-materials/manuals-bulletins-and-warranties/load-and-inflation-tables/#/ I also wonder why you are advocating running the max sidewall preshure? I would think it would be a better practise to weigh the trailer (all wheel locations or by axel) and adjust the preshure accordingly. Bill The way I read the table is axle load not single tire Look at duel weight and end that states max load per tire at 110 PSI Share this post Link to post Share on other sites
rayin Report post Posted May 21, 2019 On 5/17/2019 at 8:31 PM, WILDEBILL308 said: The weight might be slightly higher but in the example I was talking about you only have a increase in diameter of 0.2". That would be less than the difference between used and new. Without a scale I don't know how much heavier the rims are. The confusion I see is people assuming because it is a 19.5 it is bigger than a 16". While the rim is, the diameter of the package is the same. Bill Yep, same thing with car tires. A 16" tire can have the same OD as a 20" tire. https://tiresize.com/chart/ Share this post Link to post Share on other sites
