imported_alwaysoverkill

this email is directly from Toyo since i sent an email asking about the pressures of my proxes 4. many people have asked about tire pressures and been told 28-34, 40, 25 all over. so here is what toyo said about a reinforced 17" tire...40PSI. so i'm going to do 38F, 44R tire pressures (read below)


The 205/40R17 84W Proxes 4 is a "reinforced" tire in this size and requires additional air pressure to carry the equivalent load compared to your oe tires.
The recommended air pressure for the Proxes 4 is 40psi (which carries 1060lbs). Your oem P195/55R15 84V carried 1058lbs/tire at 32psi. This higher air pressure should help with handling and should reduce irregular wear common on tires that are underinflated. While the car is cornering, there is lateral weight transfer away from the center of the corner. Because the center of gravity of the car is some distance above ground, weight is removed from the inside tires and added to the outside tires. This weight transfer causes the outside springs to compress and the inside springs to extend, thus causing “Body Roll”. The outside tires are more heavily loaded. Because of body roll, the tires tend to go towards a more positive camber state, and the size of the contact patches have decreased. Remember, the cars only link to the road is the four contact patches of rubber, and their actions determine how the car handles. One way race teams compensate for the decreased contact patch is to dial in more negative camber. This will cause more rapid or irregular wear to develop though.

These are race tire vehicle set up recommendations that can give you some idea of vehicle changes and how they affect handling. (included little graph but since it won't copy/paste here are the tips for decreasing understeer as its the problem with FWD)


less front pressure and more rear pressure will decrease understeer

negative front camber and positive rear camber will decrease understeer

soften the front springs while stiffening the rear will decrease understeer

larger rear sway bar will decrease understeer

imported_GoldBadge

Good Info! Thanks for taking the time to get the right people to answer your question. It's nice to know that such a large company will still take the time to thoroughly explain their product to a consumer.

imported_alwaysoverkill

ya and fast too. i emailed toyo yesturday and got a reply that stated he needed more info to address what pressure to recommend and also recommendations to understeer (my original question). sent the info he needed and like 40 minutes later the answer.

i'm going to try a few of them too. i set my pressures at 39 front and 45 rear. also set my illuminas to 3 front, 5 rear to see if that helps the understeer. if the ride is too rough, i'll soften the shocks 1 each.

imported_GoldBadge

You should e-mail tokico and ask what the recommended damper setting is for the spring rate you have, then go from there.

1c6_eh6_t-si

decreased Understeer is great for Solo... but the average driver on the street is better of with the car biased towards more understeer so that on hard sudden movements the back end doesn't give out.
all depends on your own driving style and preference of course