Community Forums

Diesel-Lover · 03-24-2004, 05:49 PM

How do folks,

Can a GM p30 chassis take 22 inch rims

If yes which rims.

Thanks

Diesel-Lover · 03-24-2004, 05:49 PM

How do folks,

Can a GM p30 chassis take 22 inch rims

If yes which rims.

Thanks

DriVer · 03-24-2004, 06:03 PM

That's a good question that is only limited by the size of the wheel wells.

I think there's more involved than just wheels. The final drive gear is also lower in 22.5 W-Series compared to 19.5 inch W-Series. I also can't conceptualize 22.5 inch tires on an IFS P Series motorhome.

Gary RVRoamer · 03-24-2004, 07:25 PM

Increasing the tire size effectively changes the rear end ratio (because you travel further with each revolution) and also messes up the odometer and speedometer readings. And of course you need enough room in the wheel wells for the tire itself - including sharp turns and at full extension/compression of the suspension.

Adding three inches to the wheel diameter is a huge change in vehicle handling that should not be undertaken unless you really understand all the implications.

Diesel-Lover · 03-25-2004, 04:37 AM

Driver and Gary,
Thanks for the come back. The wheel wells seem to be immense and I am generally way under my max GAWRs, GVR and GCWRs . Currently I have the 225s narrow tires and the wheel width (6.0) is limiting me from wider tires. I was thinking along the lines of new wider wheels and since its a diesel the lower drive ratio is a good thing (4spd tranny).

Don't care much about the speedo as a GPS (yet to get) will give me the speed or I could see about adding a gear in line with the cable [Not a speedster in the Moho}.

She is a 99 GM Diesel Puller. Did greatly out west but now in the midwest feel like I am wasting a lot of torque going down the flat roads.

Gary RVRoamer · 03-25-2004, 08:10 AM

You can probably get a wider wheel without going to 22.5, if wider is what you want. Just have to make sure you have room on the front wells for sharp turns and in the rear for the duals (and also maintaining dual tire spacing with wider wheels/tires).

You need to look at the tire manufacturers web sites and get the circumference and width data for the tires you are considering. It will vary a bit by brand and model of tire, but probably only 0.5-1.0 inches. Then measure those wheel wells carefully in all directions and with front wheels cramped both ways as well as straight. The wheel wells look big because they allow a lot of room for suspension travel over bumps and I suspect you need to retain most, if not all, of that.

You also need to calculate the new effective rear axle ratio. The effective ratio wil be much lower and will hurt your low end performance. I suspect you will also need to modify the transmission shift points to avoid sags in power on each shift and possibly over-reving just before a shift as well.

A far better solution to your performance needs would be an overdrive unit such as the Gear Vendor Over/Under Drive. See Gear Venors. You can still go to a wider wheel/tire if you want, though I don't see any real need for that other than styling.

Diesel-Lover · 03-25-2004, 06:37 PM

Hello RVRoamer,

Great point on the suspension travel, I will have to take a look at the suspension travel issue though I can't say that I have experienced too much of that. On the lower rear end ratio issue at about 63 I am pushing around 2.5 K if I recall correctly and my thoughts were to try and get that down to 2K if possible. The GV process is a great one but can't justify the 3.3 plus expense of it. Thought the rims and tires would come in under that.

As the chevy tires sit way inside the coach looks different than the ford chassis due to the narrow track. Was thinking that the 22 wheels would/may have a larger offset to give a wider stance and or the appearance of such.

Can you explain the over-revs between shift points as that has me totally baffled.

My tires will be 5 years old at the end of this season though they look like new with no micro cracking what so ever. But I am thinking ahead and was toying with the idea of just replacing the front two some time soon or perhaps do all 6 and jump to the larger size?! By the way the front wheel well is so big that it looks like it could handle the rear axle duals on the front!

Diesel-Lover · 03-29-2004, 07:11 PM

Well folks after reading through your responses I have decided to stay with the current size tires. Thanks for sharing your knowledge and saving me pain and suffering not to mention money.

See you on the road and hear you on the radio.
Best Regards.

Swampy · 03-31-2004, 03:21 AM

I stayed with the standard 19.5 x 8 tires in the rear and went with Michellen XRV245R-19.5 in the front. Made some other changes to beef up the front suspension and the result has been much better handling. I believe the P30 chassis is too narrow for the 102" widebody Adventurer though and handling suffers for that reason.

Stan & Karen Stockdale · 09-29-2004, 07:57 AM

Hello Swampy, I am thinking of changing my tires from 19.5 to 245. where did you but your tires?

regards
Stan

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Swampy:
I stayed with the standard 19.5 x 8 tires in the rear and went with Michellen XRV245R-19.5 in the front. Made some other changes to beef up the front suspension and the result has been much better handling. I believe the P30 chassis is too narrow for the 102" widebody Adventurer though and handling suffers for that reason. <HR></BLOCKQUOTE>

LarryFR · 09-30-2004, 06:46 AM

Diesel-Lover,

You have me confused. I think you said that you had the Chevy P30 chassis. Later you seem to imply that it is a diesel. I am not aware that Chevy ever installed a diesel engine in the P30 chassis. To my knowledge, they all have big block gasoline engines, either the earlier 454 carbed engine or the later 7.4L Vortec.

Please enlighten me.

Larry

bill h · 11-03-2004, 06:41 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by LarryFR:
Diesel-Lover,

You have me confused. I think you said that you had the Chevy P30 chassis. Later you seem to imply that it is a diesel. I am not aware that Chevy ever installed a diesel engine in the P30 chassis. To my knowledge, they all have big block gasoline engines, either the earlier 454 carbed engine or the later 7.4L Vortec.

Please enlighten me.

Larry <HR></BLOCKQUOTE>

Larry, I have seen several P30 RVs with the 6.2 diesel engine. Barth, Winnebago, Southwind, etc.

Slow up the hills, but easy on fuel.

Taxman · 05-04-2007, 12:23 PM

Diesel-Lover,

I just had my FRont 6" wide 8R19.5 wheels/tires replaced with 7.5" wide 240/70R 19.5s at Rickson Tire and Wheel in Hunt Valley, MD.

And, I am delighted with the result!

They look much better and fill the wheel well nicely (no more "skinny FRont tires" on my P-30!), and the coach (1990 Airstream Land Yacht) drives/handles much better and is much quieter.

Tires are Bridgestones. Left the 8R19.5s on the rears; didn't want/need to buy new rims, don'tchaknow.

Unfortunately, I don't have Rickson's phone number handy. Their Internet site has it; Google "Rickson Tire and Wheel." Ask for Dan Richter. Tell him FRank Davis sent you.