| Author |
Message |
Glen C Winters (Wildwarrior)
New member
Username: Wildwarrior
Post Number: 33
Registered: 3-2003
| | Posted on Saturday, August 30, 2003 - 5:57 am: | |
I run my Pilot Sports @ 35psi in front 235/18 and 34psi in rear 295/18 on my 512 TR.Maybe this can give you a base line to work with. |
Martin - Cavallino Motors (Miami348ts)
Senior Member
Username: Miami348ts
Post Number: 5874
Registered: 5-2001
| | Posted on Saturday, August 30, 2003 - 1:53 am: | |
faced recently with putting new tires onm a car I personally opted NOT to use Michelin. They are the opposing F-1 team tire supplier.
As for pressure call them up and find out direct from the manufacturer and when you call tell them Montoya suc*ks! |
ES (Esnake)
New member
Username: Esnake
Post Number: 5
Registered: 7-2003
| | Posted on Saturday, August 30, 2003 - 1:26 am: | |
Hi Mitch,
First, thanks for you advise.
My 355 is only for daily use with no track (we don't have any here), of course sometime will drive a bit faster, mostly on winding roads. After reading your post, Can I just put more air at the rear, so that to reduce the understeer (more neutral)? How many PSI more? (as compare to the front)
Finally, what PSI should I use all round for that set of tire (P. sport) if I don't make any change in the car setting?
Can I just adjust the rear ride height by turning the shock collars? How?
Correct me if i asked some stupid questions, cos im new to the F world.
Thanks. |
Mitch Alsup (Mitch_alsup)
Intermediate Member
Username: Mitch_alsup
Post Number: 1006
Registered: 4-2002
| | Posted on Thursday, August 28, 2003 - 1:22 pm: | |
Front tires are original size, rear tires are 11% larger than original (265*111% = 294.1) and have the correct rolling radii (265*.4 = 106 ~= 295*.35 = 103.25) within 2%.
With 11% larger than stock rear tire the car will understeer considerably unless you use tire pressure to rebalance the car OR reset the suspension to accomplish same goal.
Since the new tires are larger in the rear, you want to reduce the stiffness at the front of the car to regain balance. Basically, you want the rear of the car to do more of the cornering work (its bigger). This can be accomplished with less front roll bar, more rear roll bar, or a higher rear ride height (probably around 4-5 turns on the shock collars).
To get this much grip out of air pressure alone will require on-the-order of 4-5 PSI difference from factory spec, and should be done on a track with a pyrometer.
If, instead of the 225/40 front, you had gone with a 245/40 front, your adjustments would have been only 1/3rd as great...... |
wm hart (Whart)
Intermediate Member
Username: Whart
Post Number: 1605
Registered: 12-2001
| | Posted on Thursday, August 28, 2003 - 1:17 pm: | |
Wrongo, Acheng. Size is not all that matters (ahem). At least Ferrari recognize this in their owner's manuals (the more recent ones, anyway). Can't give you an answer, ES. What are the recommended pressures for that brand in the manual? Note, too, that as the tires heat up under extreme driving, you may want to start out with a little less than the recommended pressures, but i will defer to the tire geeks here. (There was a significant thread on the Rennlist about this recently, which generated some controversy as to whether to follow recommended pressures, or underinflate so that the tire, when hot, did not greatly exceed recommended pressure.) |
Anthony Cheng (Acheng)
New member
Username: Acheng
Post Number: 5
Registered: 8-2003
| | Posted on Thursday, August 28, 2003 - 11:44 am: | |
I don't believe that is correct. My understanding is that the tyre pressure should only vary according to an change in tyre size. If you have stock size tyres on the car, I would just go with whatever the recommended pressure is for your car. It should be listed either in the owner's manual or somewhere on the car. |
ES (Esnake)
New member
Username: Esnake
Post Number: 4
Registered: 7-2003
| | Posted on Thursday, August 28, 2003 - 11:26 am: | |
Since different tire pressure for different brand according to owner manual, so can somebody tell me the most suitable pressure (street use)for the following:
Pilot Sport on 355
225/40/18 front
295/35/18 rear with 15mm spacer
Thanks. |
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