Tire size upgrade and 4x4 alignment question

[Whistler40]

Ok I am sorry to post yet another tire size question, alas I am so in over my head and you guys are always so dang good at answering my questions

I have actually a few questions ..in order of urgency. My van is a 2008 advance 4x4 conversion. I have had it converted last sedpt, and it runs great.

1. I currently have puny little tires(limited budget at the time of conversion and as the old tires we new left them on) ..225/75/16 on my mojave rims, and am finally buying new tires....should i change to 285/75/16 or 265/75/16. I know most people run the 285, which is also what I would like, but lots of the online tire pages warn you that running tires sizes that are more then 3% off can lead to brake failure? I do have the stock brakes, so I wasn't sure if it be safer to stay with say 265?

2...if I do get a 285/75/16 installed, do I need to get the 4x4 realigned?

3. I bought he mojave 16 inch wheels, and to fit the oem brake they require spacers. But for a spar I still have the original oem spare....counting that the spacers are installed, do I need to also change my spare so it has the correct caliper spacing? Or can I run run the oem withheld spacer on, and just have extra caliper spacing?

Ps I did check tons of tire posts and settled on the bfg a/t because xthey seem to be a good compromise for what I need....which is mainly road, 20% poorly graded fire road with a very occasional rock crawl...and as I live in whistler, bc good snow performance ...and the snowflake will help with highway patrol

[Ford_6L_E350]

Originally Posted by Whistler40

Ok I am sorry to post yet another tire size question, alas I am so in over my head and you guys are always so dang good at answering my questions

I have actually a few questions ..in order of urgency. My van is a 2008 advance 4x4 conversion. I have had it converted last sedpt, and it runs great.

1. I currently have puny little tires(limited budget at the time of conversion and as the old tires we new left them on) ..225/75/16 on my mojave rims, and am finally buying new tires....should i change to 285/75/16 or 265/75/16. I know most people run the 285, which is also what I would like, but lots of the online tire pages warn you that running tires sizes that are more then 3% off can lead to brake failure? I do have the stock brakes, so I wasn't sure if it be safer to stay with say 265?

The warning about tire sizes is primarily for mismatched sizes. If you go bigger on one end the ABS can get confused. The brakes will not know what tire size you have. Larger tires will make the brakes act as if you have more weight in the van because they have to work harder to stop the van.

2...if I do get a 285/75/16 installed, do I need to get the 4x4 realigned?

Tire size has very little effect on alignment. I changed my tire size 90,000 miles ago (from 245/70-16 to 275/70-18) and have not had a re-alignment.

3. I bought he mojave 16 inch wheels, and to fit the oem brake they require spacers. But for a spar I still have the original oem spare....counting that the spacers are installed, do I need to also change my spare so it has the correct caliper spacing? Or can I run run the oem withheld spacer on, and just have extra caliper spacing?

Trial fit the spare and check for any issues. I thought the rear spacer was to change the bolt pattern, but maybe Advanced is different.

Ps I did check tons of tire posts and settled on the bfg a/t because xthey seem to be a good compromise for what I need....which is mainly road, 20% poorly graded fire road with a very occasional rock crawl...and as I live in whistler, bc good snow performance ...and the snowflake will help with highway patrol

Hope you enjoy the van. Maybe we will see you on the road someday.

Mike

[carringb]

Spare 16" wheel will not fit over the front brake caliper. 285's are well within the range of tire sizes offered stock by Ford for the F-series. E-series rear brakes are just as big as F-series, and now you have an F front end.

If you aren't happy with braking, you can swap to Napa Premium pads. Michigan state police tested them against Ford Emergency Vehicle spec pads, and the Napa improved stopping distance and can do more 100 to 0 stops without fade.

You biggest enemy for bigger tires is probably your axle ratio. 4.10 would about the highest I would want for 285s. 3.55s I wouldn't go more than a 245 tire.

[BIGVANS]

Advanced uses the stock size brake on the front sometimes, find out from them (Randy). Test fit your stock steel rim to the front and see if it clears the caliper. Advanced does not change the rear brakes at all. The tire size will not matter at all, it's the rim inner diameter and lug nut pattern only. Most guys with that setup use the 285's. ONLY use "E" rated tires! By the way, for some reason the BFG "E" does NOT have the "Snow flake" on it like the "D" does.

[Gnarvan]

Before you plop down the money for 285's you may want to make sure you have the clearance. I have a '92 Advanced conversion and 265's are the biggest tires I could get under it without cutting the fenderwells. My buddy with a 96 Quigley wouldn't have any problem with 285's but Quigley did part body lift part suspension lift on his. Mine is all suspension lift so I don't have any additional body clearance above the axle.

[BIGVANS]

Originally Posted by Gnarvan

Before you plop down the money for 285's you may want to make sure you have the clearance. I have a '92 Advanced conversion and 265's are the biggest tires I could get under it without cutting the fenderwells. My buddy with a 96 Quigley wouldn't have any problem with 285's but Quigley did part body lift part suspension lift on his. Mine is all suspension lift so I don't have any additional body clearance above the axle.

Did Advanced move your front axle 2" forward like they normally do? If so, you should have the room no problem.

[Gnarvan]

If I just go in a straight line I wouldn't have any issues. When I turn into a parking lot with a close to lock turning radius and then compress the suspension on the curb the 265 will gently kiss the outside trailing edge of the fenderwell. No way a 285 would work.

Don't know if Advanced moved the axle forward 2". They did use a Dana 60 front end on mine which from what I've heard is a bit of a rarity.

How can I tell if it's moved forward?

[BIGVANS]

Look at the front of the frame rails, see if the front leaf spring mount is just slightly forward of the end of the frame rail. They normally weld a flat plate to the front of the frame with a plate going under the frame rail. They would have put in some spacers for the old bumper you had. You may have seen this stuff when you installed your new bumper. (Jealous by the way!)

[Gnarvan]

I don't have any of that stuff under the van. The front axle must be in the stock for a 2 wheel drive van position.

[BIGVANS]

Yes, sounds like it. That would explain the problem with 285's.

Whistler40, that stuff may apply to you too. It's worth checking into before you buy the tires.