tires - 275s switched to 295s

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tires - 275s switched to 295s

April 06, 2015, 03:21:21 pm

I'm in the process of selecting a new set of shoes. All 6 of the old ones are now 7 year old Michelin 295/80R22.5. The original owners had replaced the original Goodyears after 3 years. I never knew why. But I did find something interesting.

The coach placard has a steer axle GAWR of 14,320 with 275/80R22.5 tires (7160 per tire). I went to the Goodyear site and looked up G670s in the 275 size and they are rated at 7160 with max pressure of 125 psi. So I'm guessing that maybe the original owner loaded up the coach close to the front GAWR and did not like the ride at 125 psi. But, it is also possible that there was some other reason that I will never know.

Anyway, when he replaced the Goodyears he went with Michelins and went from 275s to 295s. Again I'm guessing for the additional load capacity factor and to run at a lower psi. The 295s are less than 1 in wider and only 1 extra inch diameter and cause no interference issues.

I'm probably going to stick with the Michelin 295s even though they are less common and more expensive. Hopefully, Herman Power in NAC can come thru for me.

Re: tires - 275s switched to 295s

Reply #1 – April 06, 2015, 03:36:39 pm

Speedo may be off.

Re: tires - 275s switched to 295s

Reply #2 – April 06, 2015, 04:11:49 pm

For comparisons try going to: Tire Size Comparison

you can insert any combination of tires and it will display the resulting changes in MPH, etc.

This is real handy when trying to compare different brands and sizes.

Re: tires - 275s switched to 295s

Reply #3 – April 06, 2015, 04:18:27 pm

Quote from: Caflashbob – April 06, 2015, 03:36:39 pm

Speedo may be off.

Bob - Speedo matches GPS so maybe they had that adjusted with the change.

Re: tires - 275s switched to 295s

Reply #4 – April 06, 2015, 05:33:00 pm

They are the same. Look it up with tuckers sites.

Re: tires - 275s switched to 295s

Reply #5 – April 06, 2015, 10:16:11 pm

Mark,
The Foretravel 2005 model year Specification Sheet/Brochure shown on BeamAlarm shows all models had 295/80R22.5 tires.
Larry

Re: tires - 275s switched to 295s

Reply #6 – April 07, 2015, 01:45:41 am

As Krush says, the two sizes are almost exactly the same. Within one tire revolution per mile or nothing the speedo or odo would notice. Tire diameters for the same size tire vary more brand to brand than any difference between 295/75 vs 275/80. The second number is just the aspect ratio (relationship of the height compared to the width) with the number 75 in 295/75 meaning the height is equal to 75 percent of it's width. A big generalization but as the second number goes up, the ride may be slightly softer but the lower number may provide a little better handling for the same tire diameter. Low profile tires found on performance cars have a low aspect ratio (number) so are very wide but not tall and might even have only a couple of inches from rim to road.

The maximum cold tire pressure should be checked as rolled on (stamped on) the Alcoa wheels. They are forged aluminum and very tough but the rim may not be designed to hold the tire bead on at higher than recommended pressures in certain test conditions.

Pierce

Re: tires - 275s switched to 295s

Reply #7 – April 07, 2015, 07:48:57 am

Quote from: krush – April 06, 2015, 05:33:00 pm

They are the same. Look it up with tuckers sites.

A Michelin 295/80R22.5 tire is not the same size as a Michelin 275/80R22.5 tire. It is significantly larger. Don't confuse a Michelin 295/80R22.5 tire with a Goodyear 295/75R22.5 tire, which is about the same outside diameter as a Michelin 275/80R22.5 tire.

Re: tires - 275s switched to 295s

Reply #8 – April 07, 2015, 08:14:32 am

20mm wider

Re: tires - 275s switched to 295s

Reply #9 – April 07, 2015, 09:58:40 am

What are the advantages of running the wider tire?
Don't know of any, but the disadvantages of wider tires are more likely to hydroplane, less grip due to reduced contact pressure, less fuel mileage.
That should start a good discussion.

Re: tires - 275s switched to 295s

Reply #10 – April 07, 2015, 10:30:30 am

The 295 are more popular thats what about every semi on the road is running and they are available everywhere.The 275 tires are pretty much seen on rvs. The 275 have a aspect ratio of 80 the 295 usually have a aspect ratio of 75 so the difference is 295x.75=221.5
275x.80=220 so there is a 1.5mm difference in the height of the tire. I would run whatever one you can get the best deal on myself.jmo

Re: tires - 275s switched to 295s

Reply #11 – April 07, 2015, 12:10:31 pm

Quote from: ltg – April 06, 2015, 10:16:11 pm

Mark,
The Foretravel 2005 model year Specification Sheet/Brochure shown on BeamAlarm shows all models had 295/80R22.5 tires.
Larry

That's what the sales brochures says but this is what the manufacturer plaque says...

Re: tires - 275s switched to 295s

Reply #12 – April 07, 2015, 12:47:13 pm

Mark,
I got that. I saw in your post that your placard stated size 275. I was just letting you know that at sometime in the 2005 model year, Foretravel switched to 295s. This was in response to your statement that you would probably stay with the 295s.
Larry

Re: tires - 275s switched to 295s

Reply #13 – April 07, 2015, 12:48:18 pm

The manufacture's plate on our 91 GV has 275/80-22.5 tires on drive and steer. It had 295/75-22.5 when I purchased the coach. I have since replaced all tires with the 295/75-22.5. My reasoning was that since I have a very flat torque curve, it was more effective to have taller tires that would give a positive increase in economy at the expense of decreased performance on up hill pulls. I doubt if the difference is noticeable, but it is there however slight. The difference in speedometer readings would be slight, but not a deciding factor since they aren't very accurate anyway. That aside, I drive using the GPS speed and the tach anyway. That reminds me, I need to replace my speed sensor, lost speedo on the way back home. Have a great day ---- Fritz

Re: tires - 275s switched to 295s

Reply #14 – April 07, 2015, 03:12:53 pm

Fritz, changing to 295/75R/22.5 will only change your speedo by .1 MPH from 20 to 50. From 60 to 90 you would be going only .2 MPH faster than with the older tires.
Circumference difference is only .4" greater.
Tire looks taller, but very little. Difference is less than 3%

Re: tires - 275s switched to 295s

Reply #15 – April 07, 2015, 10:58:25 pm

Ok taking my own post off topic: Best guess on what a dealer will offer for the 7 year old Michelins?

Re: tires - 275s switched to 295s

Reply #16 – April 07, 2015, 11:02:54 pm

Probably next to nothing

Re: tires - 275s switched to 295s

Reply #17 – April 07, 2015, 11:10:50 pm

You might be surprised. Those are still really good tires for many applications. $75 each, maybe?

Re: tires - 275s switched to 295s

Reply #18 – April 08, 2015, 12:32:07 am

Probably "offer" to charge you to dispose of them. And then turn around and sell the tires.

Re: tires - 275s switched to 295s

Reply #19 – April 08, 2015, 11:19:31 am

Quote from: fkjohns6083 – April 07, 2015, 12:48:18 pm

The manufacture's plate on our 91 GV has 275/80-22.5 tires on drive and steer. It had 295/75-22.5 when I purchased the coach. I have since replaced all tires with the 295/75-22.5.

Difference is one tire revolution per mile. Not enough for you or your speedo/odo to notice.

Pierce

Re: tires - 275s switched to 295s

Reply #20 – April 25, 2015, 01:28:22 pm

This is very interesting. I replaced my tires last year with 275/80-22.5 with the Michelin program. It looks like I could get the 295/75/22.5 tires for less money at truck shops. Someone had a concern about rubbing on the air bags. Is there a way to check that before changing tire sizes on my 2001 U270? I won't need tires for a few years but would like to save $$$ if changing to the 295/75-22.5 would work.

Thanks for the ideas.

Re: tires - 275s switched to 295s

Reply #21 – April 25, 2015, 02:21:21 pm

Ted,

They are almost exactly the same size. Within one revolution per mile. That is inside the variance between different companies for the same size tire. The aspect ratio is the difference with the 75 series slightly wider (3/4") than the 80 series.

Ours will polish the airbag bottom plate but only during certain sharp turns with the coach leaned over a bit. Never touches the bag itself. I have never been concerned about it. We do go off paved road a lot. During normal driving, there is plenty of clearance.

Generally, the wider the tire, the better they stop and handle against a very slightly softer ride with the taller 80 series tire. But differences between brands are way more than the difference between 75 and 80 aspect ratio. Our 75 series ride great at 110 psi.

Pierce

Re: tires - 275s switched to 295s

Reply #22 – April 26, 2015, 10:38:29 am

Thanks Pierce

I won't need tires for a long while, but still trying to learn. Sounds like a good idea to explore when replacing tires ( assuming I can remember it........lol).

Hope to see you at Quartzite again.

Ted

Re: tires - 275s switched to 295s

Reply #23 – April 26, 2015, 10:59:08 am

Are 11RX22.5's even made any more ? That was the standard tire on trucks and trailers for years until the Metric designations became the standard.
Gary B

Re: tires - 275s switched to 295s

Reply #24 – April 26, 2015, 11:51:01 am

Time for a little thought, IF the wider tire proves provide such better traction, then WHY do the truckers with the wide singles hate them so much when the road gets a little slick, snowy or wet ?

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