Theoretical Max Rear Tire Width

[Dan]

Will the rear height adjustment trick in our cars work well enough to give us enough lift to install tires that extend beyond the wheelwells without rubbing with each bump?

My thinking is that this might be a way to install a much wider tire in the car for drag use.

-Dan

[Warpath]

In order to do something like that and not get the tires to rub during each bump, I think the springs would be overinflated. You don't want the spring to go to its max height point by adding air. It will destroy the spring. Besides that, the springs may be so stiff that vehicle skips over the bumps instead of absorbing them making it a white knuckle ride. My advise is not to take the risk of the unknowns. If you really want wider tires, move the shocks inboard of the frame rails (they won't be as efficient though). If that isn't enough, mini tub it and maybe pinch the frame.

[Joe Walsh]

I think that the overinflated rear air suspension would really hurt your 'weight transfer' and negate any extra traction from the wider tires...BTW you can mount Nitto P305 Drag Radials on widened (9.5") rims...how wide a tire do you want to run? (Vipers run 335's and they are STEAMROLLERS!)

[cyclone03]

Will the rear height adjustment trick in our cars work well enough to give us enough lift to install tires that extend beyond the wheelwells without rubbing with each bump?

My thinking is that this might be a way to install a much wider tire in the car for drag use.

-Dan


I think if you ran tires that stick out so far you have to raise the back end to clear them you may lose the benifit of those wide tires because of the screwed up geometry of the rear suspention.
In other words I bet it will spin like mad.

[FordNut]

Just get smaller size rims (skateboard style) and go as wide as you want!

[Joe Walsh]

Do what I saw at the dragstrip once....a redneck in a late 70s Camaro with an 'open differential' mounted a REALLY WIDE tire on the right side ONLY! Hey...it kinda worked and I'm sure it cost less than running a 'Posi'.

[Dan]

I was just asking from the point of view of on the strip.

-Dan

[SergntMac]

We've been down this road before, and it's full of opinion. Here's mine.

My tire advice comes from Brad Grissom, Kenny Brown's "Doctor Tire." Brad says that the maximum tire width on a 9.5" wheel is 295 wide, for a correct fit, and allowing for full tread footprint on the pavement. Larger sizes fit on the car, yes. But, not all of the tread meets the pavement. Taking Brad's advice, went with the Pirellis in 285/45/18 (295 not available in the tire I wanted) Mounted on 9.5" wheels from Lidio, on the rear full time.

There is evidence of contact between the upper shock and the tires, but it's very light. Dirt rubbed off the shock, but not deep enough to burn into the shock paint. Likewise the brake hose mounts, light dirt scrub, nothing more.

I find matching contact patches on the inside of the tires, but not forming a complete circle around the circumfrence of the tire. IMHO, I'm rubbing in hard turns that occur before the air suspension balances itself, such as pulling out of my garage (very steep incline, lock to lock turns), or from tight parking spaces.

IMHO, this scrubbing would be much worse with a larger size, and my advice is 285/295 is your width limit. This is still a lot of rubber on the road, and if you're adding genuine drag radials, you should expect a lot of performance from these sizes. Zack uses BFGs in 275/35 and he's got quite a launch going on...

Just my .02c...

[Warpath]

I posted something similar in another thread. Tire manufacturers specify the required wheel width for their tires in their specs. The 295s I have require 10 to 11.5 inch wide wheel. They are g-Force T/A KD 295/35/18s. Here are my specs:

http://www.bfgoodrichtires.com/assets/pdf/gforce_ta_kd.pdf

[SergntMac]

I posted something similar in another thread. Tire manufacturers specify the required wheel width for their tires in their specs. The 295s I have require 10 to 11.5 inch wide wheel. They are g-Force T/A KD 295/35/18s.
Yeah, I hear ya, it get a bit confusing, Pirelli says 9.0 to 10.0 for their 295s. Maybe it's something to do with sidewall construction?

[Warpath]

I couldn't tell ya. I'm sure sidewall construction has some part in it. I can imagine if it is very stiff, a narrower wheel would bow the treads. I'm sure everything else has a part in it too (aspect ratio, section width). But, I think load capacity may be reduced if the width is not correct - cornering stiffness too probably which would mess with oversteer/understeer. I only know enough about tires to make things more confusing. :) So, I think its best to stick with what the manufacturer specifies.