Hi AllisonMan,


New Member
I am considering changing tire size from 235 x 22.5" to 255 x 22.5" and was told by the factory rep this was no problem. My rig is a 37 foot Tradewinds M/H. Before talking to him, I was only thinking about changing the front tires to give me blow out protection. He said this was OK to do all the way around as tire clearance etc would be fine. If I did this on the back, would the tranny be affected? The rep said climbing hills would not be a problem. I would like your input here as I am not sure that I should do this on the back and I value your opinion on the tranny.
Also, I changed my tranny to synthetic at 25000 miles and bought the parts, filters etc. at an Allison dealer. He told me to do an extended drain to allow more fluid to be removed. I did this drain for 5 hours and replaced 20 qts. of fluid. I did not know about the return line removal from the torque converter and he never mentioned it. I read about the torque converter drain here. He indicated that this change over would give me about 80% C/O to SYN and that the next C/O would give me 100% SYN. He did also say that I did not have to wait for 25000 miles to change again and meet the 100% SYN requirement. I have documentation that the tranny service filter change was done at 5000 miles (by Allison sign off). The fluid that was drained looked fresh and clean, no discoloration.
I bought this rig with 7800 miles and do most of the servicing myself.I have been pleased with the performance. The tranny shifts fine and the tower check shows A-OK. I did a 27 mile run before making the tower check and I can tell it runs cooler as you can not wait very long after shutdown or you get a cold sensor code. Thanx for your time and effort with this column and by giving M/H owners like myself a chance to get the job done right and save money.
Thanks again.


New Member
Hi AllisonMan,

Hello Tradewinds,
About tire size. The gradability, road speed and speedometer will change slightly. The best step you can take is to go to your nearest Allison dealer or distributor and request a SCAAN run. They will feed numbers into their computer and it will do the calculations and it will tell you whether ot not it is ok for this change. I cannot do because we need a lot of information height, weight, engine numbers and many more.
On the Transynde oil change, that person didn't know what he was telling you. Extended drain? I had to laugh at that one never heard that before. The correct way would be to service transmission with filters, then disconnect the cooler return line (one with arrow pointing towards transmission) and after you have added about 4 gallons, have someone go inside coach with brakes on, windows open and start until you pump out about 1-2 gallons of oil out of the hose into a bucket. This will push the oil out of the torque converter. This would have given you 90-95% synthetic oil (we have tested)which is good for 4 years or 100,000 miles. Make sure you do oil samples aprox every 500 hrs or 25,000 miles and request Transynde percentage when you send in the sample. Thanks for the questions and have a great day!