2017 Allegro 32 SA Tire pressure

[Peter M]

I am trying to dial in my 32 SA tire pressure. I am using the following Michelin tire inflation chart for my coach .

Michelin RV Tires | View Michelin RV Tires load and inflation tables for motorhomes and recreational vehicles. | Michelin RV Tires

My coach is Fitted with 255/80 22.5 XRV tires. The dealer had 94 psi in all 6 tires . Was unable to get a 4 corner weight and settled for F & R axle weight.
With a loaded coach the following axle weights are F 8200 , R 13620.Gross F limit 9000 and gross rear 15500.

So we divide the numbers in half for the front corners @ 4100/ side rear @6810/ side.
According to the chart I could be setting the pressure at 80 psi F & R.

I will drop the pressure to 85 and test ride today, reducing the pressure by 9psi.
Side Note : In the last issue of Roughing it smoothly Henderson RV in Oregon did a big write up on the 32 sa regarding chassis modification. Fully loaded they run 80 psi !
So what pressure are you 32 sa owners running ?

[4x4van]

Since you don't have individual corner weights, I would go with a 53%-47% split on the axles to account for side-to-side variations. That gives you 4346 lbs front, 7219 lbs rear. So 85psi front and 75psi rear according to the table.

[Peter M]

Originally Posted by 4x4van

Since you don't have individual corner weights, I would go with a 53%-47% split on the axles to account for side-to-side variations. That gives you 4346 lbs front, 7219 lbs rear. So 85psi front and 75psi rear according to the table.

4x4 thanks for the suggestion. Test ride noted the following. Horizontal road seams, sharp edge bumps, potholes were much less harsh and quite plush. Any encounters with longitudinal road seams or ruts did not shift the coach off line. Steering was more precise .
The only negative was a noticeable increase in lean of the coach on off camber roads and some turns. Most pronounced with tight turning @ low speed. Overall impression, the tires were overinflated at 94 psi. The reduction in air pressure did allow for a more relaxed drive and a plush ride. Although @ 94 psi I was comfortable.
My coach has Safe T Steer, Rear track bar and front and rear sumo springs.

I feel the need to up the air pressure by 2-3 psi @ 88 psi F & R, a retest to follow Saturday.

[Peter M]

Originally Posted by 4x4van

Since you don't have individual corner weights, I would go with a 53%-47% split on the axles to account for side-to-side variations. That gives you 4346 lbs front, 7219 lbs rear. So 85psi front and 75psi rear according to the table.

4x4 thanks for the suggestion. Test ride noted the following. Horizontal road seams, sharp edge bumps, potholes were much less harsh and quite plush. Any encounters with longitudinal road seams or ruts did not shift the coach off line. Steering was more precise .
The only negative was a noticeable increase in lean of the coach on off camber roads and some turns. Most pronounced with tight turning @ low speed. Overall impression, the tires were overinflated at 94 psi. The reduction in air pressure did allow for a more relaxed drive and a plush ride. Although @ 94 psi I was comfortable.
My coach has Safe T Steer, Rear track bar and front and rear sumo springs.

I feel the need to up the air pressure by 2-3 psi F & R to 88 psi, a retest to follow Saturday.

[4x4van]

Many people bump their pressure up by an additional 5psi over the table value for an added safety buffer. At the 53% weights, both your front and rear weights are about midway in the table for the pressures I suggested, so you should be good at those pressures. Although an additional 2-3psi certainly won't hurt.

[Peter M]

Originally Posted by 4x4van

Many people bump their pressure up by an additional 5psi over the table value for an added safety buffer. At the 53% weights, both your front and rear weights are about midway in the table for the pressures I suggested, so you should be good at those pressures. Although an additional 2-3psi certainly won't hurt.

..Thanks 4x4, My next test will be interesting. If the lateral movement tightens up my next refinement will be Koni's

[jpstakun]

I have a 2015 Allegro Open Road 32SA with the same tires. The sticker on the door jam says inflate to 100 psi. I inflate to 102 psi. Your idea to go down to 85 will undoubtably go down in flames. Don't do it. I've tried reducing air pressure to improve the ride. I can't tell the difference. Better to err on the safe side to inflate closer to the max allowable on the sidewall of the tire. After 20 years, I've never had a blowout.

[DWRichard]

Originally Posted by jpstakun

I have a 2015 Allegro Open Road 32SA with the same tires. The sticker on the door jam says inflate to 100 psi. I inflate to 102 psi. Your idea to go down to 85 will undoubtably go down in flames. Don't do it. I've tried reducing air pressure to improve the ride. I can't tell the difference. Better to err on the safe side to inflate closer to the max allowable on the sidewall of the tire. After 20 years, I've never had a blowout.

The tire expert over at TRVN would seriously disagree with you, and he has double your experience time wise, all in the tire business.

You set your pressure based on tire specs and weight on them. There's a reason why there are charts for inflation based on four corner and axle weights.

[Pa Miller]

100 front 95 rears mine rides smooth .
Under inflated tires scare me more with loads . YOMV

[Peter M]

Originally Posted by jpstakun

I have a 2015 Allegro Open Road 32SA with the same tires. The sticker on the door jam says inflate to 100 psi. I inflate to 102 psi. Your idea to go down to 85 will undoubtably go down in flames. Don't do it. I've tried reducing air pressure to improve the ride. I can't tell the difference. Better to err on the safe side to inflate closer to the max allowable on the sidewall of the tire. After 20 years, I've never had a blowout.

Thanks for the feedback. But as mentioned prior my coach had 94 psi at all wheels from the dealer. First test at 85 psi noted a plusher ride and a little to much side to side lean. Also noted going up to 88 psi from 85. I will test Saturday..
Ah the flame bit has no merit ,you need to reference the Michelin chart in my first post with axel weights..

[flywithcoop]

I always follow the manufactures recommendation on tire inflation pressures as a starting point Tiffin says 100 cold psi so that is where I started and have stayed at 100 psi. The tires tell you the true inflation story. After 30,000 miles my tires have even wear across the tread. Both front and rear have a perfect wear pattern. No outer edge or center line wear is seen. Under inflated tires wear out on the outer edges and over inflated wear out the center tread. Look at your tires to see how they are wearing. On my Jeep GC the tires were wearing out on the outer edges with the recommended 36 psi cold pressure at 30,000 miles on the odometer and 15,000 towing miles. The outer edge wear could be caused by the towing miles so I inflated them to 38 psi to compensate for the outer edge wear.
Be careful of over inflating tires as the pressure increases as the temperature increases. this can cause a blow out. Never exceed the max pressure rating.

[Peter M]

Originally Posted by flywithcoop

I always follow the manufactures recommendation on tire inflation pressures as a starting point Tiffin says 100 cold psi so that is where I started and have stayed at 100 psi. The tires tell you the true inflation story. After 30,000 miles my tires have even wear across the tread. Both front and rear have a perfect wear pattern. No outer edge or center line wear is seen. Under inflated tires wear out on the outer edges and over inflated wear out the center tread. Look at your tires to see how they are wearing. On my Jeep GC the tires were wearing out on the outer edges with the recommended 36 psi cold pressure at 30,000 miles on the odometer and 15,000 towing miles. The outer edge wear could be caused by the towing miles so I inflated them to 38 psi to compensate for the outer edge wear.
Be careful of over inflating tires as the pressure increases as the temperature increases. this can cause a blow out. Never exceed the max pressure rating.

Mike are you referring to the 32SA ?
My coach at 94 psi there was a harsh ride . I will also say when bleeding air out of the tires 1 psi is a lot of air.

[Peter M]

So far 88 front 90 rear works well. And there is not a chnce of going down in flames.
Over inflation causes handlings woes

[ALinMaine]

I did a 500 mile trip at 85 with full water and propane. Glad I did camp had water issues. Front end felt mushy. This trip at 90 - front feels better. Back no real difference.