tires again

[sledhead]

here is what I was thinking !!  it is time to replace my drive tires and why not replace my 315 80 r 22.5 tires I have now with 11 r 22.5 tires as I can get a better price on the 11 r's plus it would help on extra power as I have a 333 rear end with a 6v92ta ht 740 auto . right now at 62 mph I am at about 1650 rpm and I know my engine makes the best power , mileage at about 1800 rpm . my weight when loaded and full with fuel is 34,600 lbs + toad and trailer of 6000 lbs , front is 12200 lbs and rear including tag is 22400 lbs so less 5000 - 7500 lbs for the tag the 11 r 's can hold the weight of the aprox. 17400 lbs on the drive's . I have 4 corner adjustable air bags and I could raise up the rear bags to adjust for the lower height of the 11 r 's .

so can one of you guys tell me if the different revs. per mile would make any difference on raising my engine r p m when cruising and if this would work ??

thanks   dave   

[luvrbus]

You need to check the wheel width before buying you may have 9 inch wide wheels for the 315/80's and the 11R x 22.5 needs the 8-1/4 wide wheels

[sledhead]

rims are 8.25 now

dave

[Dave5Cs]

Dave your good to go.
We did it last year. You lose a little top end but not enough to notice. It throws your speedo off a little but we use my phone anyway for speedo GPS. Climbs hills better and a lot less weight to life off and on when pulling them to check brakes etc. Toyo's nice tires.
Dave5Cs

[sledhead]

thanks Clifford and Dave

is there a speed chart for the different tire diameter     315 80 r 22.5 and 11 r 80  22 ( 275 80 r 22.5 )

I would like to know at 62 mph what the rpm on the engine would be

thanks   dave

[luvrbus]

There are tons of easy to use calculators on the net but you need to know the diameter of the tires and that is going to vary from each tire manufacture.I would guess you will have a rpm increase of 10 to 20 rpm for the same speed  

[moosemanusa]

I've just gone through all this.. tires on our 8 were/are dry rotted.. I struck gold and I guess the local fire trucks use 315/80/22.5's and they just switches there's tires out.. paid $150 for michelins (that look new) and are not all that old either.

we just called around and got lucky with one shop. might be the same in your area..

[TomC]

3.33 with 11R-22.5 (501 rpm) at 62mph will be 1,724rpm-perfect!

[luvrbus]

If TomC is correct that going to cost you some fuel mileage to run smaller tires you can give up a little but I wouldn't give up 75 rpm,I like the 1650 rpm if the engine is happy there 

[sledhead]

thanks Tom that helps a lot and was what I was looking four . in a perfect world I have had my coach as fast a 87 mph so to loose a little top end won't hurt at all and to have a little more rpm at cruising speed will be good even if it cost's a little for millage , but it might even help ? time will tell   

thanks   dave