Hello I have a 2001 2500 24 valve. It's got the six speed and high out put motor. I have 285/65 16r tires right now , it's reving at 1950 rpm on the high way . I want to go up to 35" tired or even larger than that.... My question is how much will my Rpm's change ? And what will happen to my mpg . I should also ad , it has a 65+ edge chip 5" stacks and a big aef air cleaner. 340,000 km on the clock

 

hope you have an aftermarket lift pump and fuel pressure gauge on there with the edge box...

anyway...your rpm's will lower a few hundred, however your fuel economy will lower as well from having to turn a larger tire mass.

you will also need a leveling kit and offset wheels to fully clear 35" tires or 315/75R16s..(close metric equiv)

without the offset and just the leveling kit, it will rub slightly on the suspension and fenders at full steer...

with offset wheels moving them outward a bit, it will clear everything but be close to rubbing on the inner fender at full steer, but it will take a decent bump to get it to rub at full steer...

hope that helps...

Personally I think if bigger tires is what you want, go for it...

I run 315/75R16 BFG KM2s on mine with offset wheels and leveling spacers up front.

I'm at 15mpg, but used to get 17-18mpg average before I modified the hell out of the truck...I get 15mpg now because of compound twins and huge injectors...

 

Thanks for the reply, I got a 2" levelling kit on her. Why do I need gauges with that chip? Both my pumps went 8 month ago. Now I got a pump in my tank

 

low fuel pressure is the #1 killer of vp44 injection pumps...

having a fuel pressure gauge on there is a good idea to make sure you are never starving your injection pump for fuel.

it needs to see over 10psi at all times to prevent excessive wear and heat from shorting its life.

While the in-tank retrofit pumps are better than the block mounted carter lift pumps, they are still inadequate to keep up with the fuel demand from aftermarket performance mods, however you may be lucky and not be dipping below 10psi.

only a fuel pressure gauge on there will tell...

 

I would set yourself up with a good lift pump. I was only getting 8 psi with the intank pump. Installed a Raptor 150 and set it to 15psi with the adjustable screw. Look at the size difference!

 

also if you get larger tires keep an eye and check your front end perodicly. they will get chewed up by a bad wheel bearing or steering components.

 

Any tire will get chewed up by a bad front end they don't have to be big

 

yes any tire will get ruined.... but with bigger ones it seems to happen faster and is more noticeable... also there more expensive, usually by alot as im sure you know, so why not check it periodically instead of waiting to watch the tread.

 

So I put the 35 s on. It revs at 1800 now at 100 km/hr and the mpg increased by quite a bit

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Mpg increased on highway I should add. In town it has gone down