Question about bigget A/T tires

[kopfjaegger]

Hi all,

I looked around to see if there was a post that answered this question, but found all kinds of different answers and got a bit confused so I'll just go ahead and ask:

I came accross a set of A/T 275/65R18's for free, no rims. They were used for like 6 months. My 70 Chevy K20 uses 16's and it needs tires. I left the suspension alone but installed a 3 inch body lift. I may do a suspension lift in the future, but I'm leaving it alone for now.

I came accross a $200 set of Pro Comp Xtreme rims that would fit the truck and tires. My question is; is there a drawback to switching to a bigger tire like that in terms of safety, fuel consumption, and the like? How hard or easy is it to alter the speedometer to give a true reading?

I mocked the tires on and they seem to clear all around so that is not a concern. Are there any other concerns I should look at? I know that 18's will be more expensive as far as replacement costs. The tires are just collecting dust in my garage and I would like to use them if it is beneficial. If not, I need to get rid of them before they rot in place. The truck will be used as a working truck with occasional use for light off road type applications, and maybe a highway trip here and there... not mudding or rockcrawling. I'll still have the 16 in rims, so I can go back to that size tire if necessary, but I would like to know the pros and cons.

I think I covered everything, any help anyone can give will be much appreciated.

Thank you in advance.

K

[69GMCLonghorn]

Here's some food for thought.

Smaller sidewalls typically cause a harsher ride. How much harsher and whether it's tolerable is what you will have to decide. Also for 4 wheeling, I've always been more in favor of a bigger sidewall. Maybe it's old school thinking, but when you're crawling over rocks, etc, those sidewalls allow the tire to form to the shape of things, rather than dent/damage a rim. So I guess it depends on how hard core you're driving it and over what type of terrain.

[kopfjaegger]

Thanks 69GMC,

I don't think my kind of driving would be considered hard core. Like I said, probably just around the farm for work, some light off roading, no river crossings or the like, and perhaps 50 or 60 mile trips once in a while. My truck was pretty much an all around, beat up, old clunker truck before I took her apart for her make-over.

The tires are A/T's and they have a pretty tall sidewall.

Thanks for your quick answer

Kopfjaegger

"From this day to the ending of the world,
But we in it shall be remembered,
We few, we happy few, we band of brothers."

[unclewatts]

One problem I can think of is that they might rub inside on the suspension on hard (lock or near lock) turns. As to your speedo question, if after you find that the speedo is indeed off you will have to change out the drive gear located in the transmission to a different color.

[kopfjaegger]

Thanks Unclewatts,

In addition to that are there any thoughts on torque or fuel mileage? I know there would be a change in mileage, I guess it would be more of a gas guzzler. I don't know if I would lose torque at the wheels by increasing the diameter.

Thanks for your answer. I appreciate it.

K

"From this day to the ending of the world,
But we in it shall be remembered,
We few, we happy few, we band of brothers."

[lineman33]

Depending on your wheel offset you will rub on your drag link while turning right unless you do some major drag link adjustments

[kopfjaegger]

Thanks for your help guys, I appreciate it. I decided to scrap the idea and perhaps try to sell the tires off. It seems that I do have the clearance, but I don't wanna take the chance.

I'll be posting pics of my truck here pretty soon.



"From this day to the ending of the world,
But we in it shall be remembered,
We few, we happy few, we band of brothers."