tire sizes

porschekiller · #1 10-05-2007, 09:01 PM

i thought i should share some valuable info. first, '97+ dodge avenger wheels fit svx's from 15 to 20" akuza creations. today i fitted 245/50-16 tires. there is 2,100 lbs over the front wheels which is equivalent to a ferrari 612 scaglietti with 50/50 distribution and 245/40-19 front tires, which are equal to a 245/50-17 ('08 acura rl) or 245/45-18 (jag xk8). the height is crucial for response dynamics, especially in autocross. also, the bmw m6 uses 255/40-19 front with close to 2100 lbs front. i'm converting to rwd and 255/50-16 rear tires-think bmw m3 255/40-18. also ccrengines.com has aircraft quality 3.3L with a 3 yr/36k m warranty and custom cams for $3,605. today i bought a set of enkei wheels with falken z rated a/s tires for under $800 from discounttiredirect. tomssvx is the chief engineer and i have alot of faith in him.

wawazat?? · #2 10-05-2007, 11:51 PM

I'm sorry but I find this post is difficult to read. Yes a number of cars use the same 5x114.3mm (4.5") bolt pattern as the SVX. I'm confused by your statements on weight distribution on the other cars you refer to compared to the SVX. While our front end end weighs close to that figure the rear is much lighter and we are nowhere near 50/50 front/rear balance.

I agree the aspect ratio and subsequent tire height is crucial to response in autocross as I do it regularly with my SVX (including this Sunday), but I'm really lost by the rest of your post

Todd

porschekiller · #3 10-07-2007, 06:46 PM

the rear weight is irrelevant in a front heavy car. 75% of the braking is in the front and all the steering and control is in the front unlike a porsche you can steer with the throttle with the heavy rear. for example the new fwd monte carlo v8 uses 255 front tires and 235 rear tires. understeer is the issue, not oversteer, but i prefer the wide look in the back, but for autocross you may want to go narrower in the rear for balance as a porsche 60/40 does in the front: '92 911 turbo 255 rear, 205 front. i've also found that going lower profile than a 235/40 is not good for autocross, so ideal tire sizes for autocross would be 245/40-19 front and 225/45-19 rear.

sicksubie · #4 10-07-2007, 06:53 PM

rear weight is irrelevant???? Uhm not really. Rear weight helps the balance and in a way can help with understeer. If you have a better balanced car (weight in the rear) you can do things to promote oversteer and eventually get a car that breaks away evenly in corners. Also, no offense but nothing about the tires that you mentioned is new. Do a search and you will find that wheel fitment and tires is one of the biggest topics of discussion here.

TomsSVX · #5 10-07-2007, 06:55 PM

a smaller rim is also more ideal... a 17" rim with stock diameter tires are very effective

tom

porschekiller · #6 10-07-2007, 07:02 PM

the porsche cayman comes with a 205/55-17 that can be use in the rear instead of adding wieght to balance a car which is never good. an svx would weigh over 4200 lbs. balanced. actions always speak louder than words.

TomsSVX · #7 10-07-2007, 07:13 PM

Quote:

Originally Posted by porschekiller

the porsche cayman comes with a 205/55-17 that can be use in the rear instead of adding wieght to balance a car which is never good. an svx would weigh over 4200 lbs. balanced. actions always speak louder than words.

HUH? You are best off with some 245/255 with a moderate sidewall. There are things to do like moving the battery to the trunk to try and balance some more weight. There is also ditching the ABS/washerfluid tank & pump/ air conditioning/ auto for a 5mt to lose more weight off the front. also the fiberglass hood will shave som ppounds up there

Tom

wawazat?? · #8 10-07-2007, 07:36 PM

Quote:

Originally Posted by porschekiller

the rear weight is irrelevant in a front heavy car. 75% of the braking is in the front and all the steering and control is in the front unlike a porsche you can steer with the throttle with the heavy rear. for example the new fwd monte carlo v8 uses 255 front tires and 235 rear tires. understeer is the issue, not oversteer, but i prefer the wide look in the back, but for autocross you may want to go narrower in the rear for balance as a porsche 60/40 does in the front: '92 911 turbo 255 rear, 205 front. i've also found that going lower profile than a 235/40 is not good for autocross, so ideal tire sizes for autocross would be 245/40-19 front and 225/45-19 rear.

Uh, rear weight is relevant in any car as front to rear weight (load) balance is the key. Also, all of your examples of different tire sizes don't apply to anyone here except your car when it becomes RWD and the FWD guys we have here. The AWD cars require the use of the same size tires to avoid catastrophic transmision/differential failure. Finally, 19" I can think of no instance where a 19" wheel and tire combination is ideal for autocross except when you are running a Stock class car that has 19" wheels as OEM fitment. The additional rotational inertia and weight of a larger wheel will offset any gains expected from a 19" tire. Additonally, I believe there are few autocross capable tires in 19"

porschekiller · #9 10-07-2007, 07:42 PM

i decided to keep the awd because there is not much change in weight. the awd still has the balance of a fwd car 60/40 w/ driver.

porschekiller · #10 10-07-2007, 07:45 PM

i can only post once

TomsSVX · #11 10-07-2007, 08:13 PM

Nitrous controller

This would be a good option without spending too much

Tom

porschekiller · #12 10-07-2007, 09:35 PM

the first day you said you were looking for a trans between 500-1500, because it was better to break a wrx 5sp than buy an sti 5 sp. long weekend?

porschekiller · #13 10-07-2007, 09:59 PM

check out the bolt on kit for lambo doors. it's only $370 and has some good reviews.

TomsSVX · #14 10-08-2007, 09:53 AM

yes, but you had told me you wanted to go with an R/A equipt sti 5mt... i think you will do just fine with an 04+ wrx trans. you had told me you found an STI 5mt for 2k and I thought you were going to buy it. If this is all wrong, please let me know so I can continue my searching. where are you seeing a bolt on lambo door kit for an SVX??

Tom

porschekiller · #15 10-08-2007, 01:25 PM

this place has bolt on kits for $370 with good reviews. the 5sp was a wrx 2.0 for 1995, now i got one for 995 in texas. can you do better? can i send you speakers to put in also?