Please do not laugh this issue has caused me much headache and i want to know if anyone has seen the same.

My car is open source tuned with ecu flash. I have a tune that has worked flawless for three years of auto cross, drag racing, and track days. Car is driven year round in Erie Pa where temperatures range from -30 to 90. No problems.

Until my recent set of 275 35 18 Dunlop direzza z2 became worn.

My car went from running 26 psi to 30-33 psi spikes.

Issue went away when winter came an I threw on my snow tires.

This was after i tried swapping the MAF, the stock boost control solenoids, and replaced all vacuum lines that bleed air from the wastegate.

The wastegate opens as it should at about 14 psi of pressure as i tested it.

No matter what i tried the issue did not go away until i changed to a larger diameter tire. It stopped immediately.

Note i have high flow filter and cat back, no other mods.

Anyone have input? Ideas? Suggestions (other than a new tune as i likely will if nothing changes)?

Has anyone seen this before.

 

First I ever heard of something like that. Just get decent tires if that's what makes the problem go away.

 

tune your car.

 

My boost stays the same when I go from 25.03" diameter tire to a 26.0. Never heard of such a thing.