[Agile]

I basically have a stock '91 with only a cold-air intake and custom exhaust. I'm throwing on some 17" wheels that weigh like 20lbs each . I have the SSAC header sitting in my basement ready to be installed. From what I understand, 17"wheels will slow the car down significantly. Is this true? I'm wondering if the header will make up for this loss.

 

[Kosan]

it will bog down the car. but for me, not enuff to keep the stockers. i prefer 17's your headers should make up the difference.

 

[seize]

Don't be too quick to judge.
Stock 14x6 weigh 16.5 lbs
with 14x7 that weight 19.3 (practically 20lbs)
Depending on the weight of the tires those 20lbs 17" might not be much worse than the original 14x7s.

 

[Seth W]

the cars not fast by any means so may as well put some decent rubber/rims on it. Finding good tires in 14-15 sucks to find anyways.

 

[bowlofrice]

^^ sadly but true.

 

[Trixter747]

I always forget how heavy my 17's are until I put my stockers back on. Maybe that's just 'cause I'm running Kumho 712's, which are far from a light weight tire. It'll really depend on the tire/wheel setup you're specifically going to be using. Mine slowed me down a bit, but I love the improvement in handling so it's worth it to me.

 

[hijinx]

It's not the comparable weight of the wheels which will slow you down. It's essentially the increase in size which slows the car down. A smaller wheel and tire combo has less reciprocating mass, which means that the tire can spin faster and at more rpms with less power put to it. The 17's will cause a loss of acceleration, even in though in the grand scheme of things they weigh approximately the same as the 14s you have stock.
-TY

 

[MR2Quick]

Once JekylandHyde or Bill finds this they will explain in more detail. but for some hardcore stats

93 N/A with FULL HME exhaust (header, hi-flo cat, catback) TomsMR2 intake w/ K&N X-Flo filter.

On track day, i ran my best with my 15's - 15.257.
The same day, i ran with my 17's and couldn't do better than 15.5.
and each run was approximately the same.

Its all about rolling mass. So if you are going to be putting on 17's for performance, then get the lightest wheel you can possibly get. Otherwise its just for show. and by no means get 18's... or as i have seen before, 20's... that was an eyeful.

 

[rdyzz]

i'm planning on 16's but have yet to find a good style. even if putting on bigger rims wouldn't the speed still be close to the same depening on the profile of the tires you use? anyone know if a +48mm offset will fit mr2's 16x7 or 16x7.5

 

[TomsMR2]

when i bought the car i had 16x6.5's on all corners with a 55 offset! HORRIBLE. the car was dangerous to drive, but it looked nice... switching from those aweful rims to oem 91 rims made a bigger impact (for the better) than putting my illuminas in!

get the right offset, and get the right rims for your car.

 

[JekylandHyde]

With wheels, acceleration is affected in many ways, here are just a few:
1. The weight of the wheel & tire. Rotating weight matters MUCH more than sprung weight (weight above the springs ~ interior, A/c, etc ...)

2. The overall diameter of the combination. A smaller over all diameter accelerates faster, but you lose mph per gear.

3. Sidewall design. For "Drag style" launches, you generally would prefer more sidewall, especially if it is squishier. A low profile 17 is terrible for drag racing.

IF you happen to have a 15 and 17 combination that are the SAME overall diameter and have the SAME weight and happen to have the SAME "sidewall launch capabilities" then there should not be any performance gain/loss.

*theoretically* ... and yes, there are other factors. This is simplified.

As for the initial question:
The header SHOULD add real HP.
The rim/tire combination might hurt or help your launching.

Generally speaking, for regular street tires, you will have improved handling with the 17" with low profiles.

 

[Agile]

Why was it dangerous to drive?

 

[jarhead_jr]

Thats just Tom's Toyota stock is holyer than thou talk...joking. Not sure why the tires would make it extremely dangerous, but I do have this to say about larger size tires. If you overall diameter increases, you WILL lose some acceleration as you decrease the force the tire can produce against the road. Remember all the wheel/tire does is convert the torque of the drive shaft to a linear motion. For a constant torque to your wheel hub, a larger wheel and tire diameter will decrease the force against the road to get you moving. As for same overall diameter with larger rim and smaller tire, you have to look at where is the weight located. You have to look at the weight of the tire rubber vs weight of the rim individually. Suppose the tire rubber weights more per radial inch than the rim, then you would benifit to go with larger rims. If the tire weights less per radial inch, then you would be best to go with smaller rim larger tire.

What does all of this mean? Probably not to much really. Besides you said your throwing on a header. Do yourself a favor and keep your old rims and tires, swap out the header and try running both rims to see for yourself which you like better. Hope this helps.

 

[rdyzz]

I'm looking into the rota slipstream 16x7 it goes in a 40mm+ off set 45mm+ offset and 48mm+offset witch one would fit the mr2 best the 40? these weigh 14.5lbs I belive I know they are spoon knock offs but the 5zigen pro N1's i was looking at only had a 5x14.3 bolt pattern in 17's. im pretty set on 16's looking at running toyo proxes t1-s 205/50/16 fr and 225/45/16 rr.

 

[mr2d2]

Not sure why the tires would make it extremely dangerous,

stock is 14x7 with a 45 offset. mine were 16x6.5 with a 55 offset... i had 20 mm less offset and 1 inch narrower total rim... the rear width was MUCH narrower in the back from stock, while the front was reletively the same.. this makes it unstable and very easy to spin... literally night and day from those to stock.

proper offset is important as hell. dont put narrow ass rims on your car! you can find tons of tires from tons of makers in 205/xx/15 and 225/xx/15.. theres good tires out there for 15's!

edit: This is Tom... i have no idea how i ended up on this log on!

 

[Agile]

Ah, makes much sense. I forget that the bigger the offset, the narrower it is. I'm yet to figure out where those numbers come from...

As stated, the NA is slow so I'm not worried enough to be rolling on 14"s for better acceleration. I mean, 17"s just look too good not to get them. However, I wanted to feel the gain that everyone was talking about after putting the SSAC header on. I didn't wanna miss out on that.

Thanks for the replies everyone!

 

[Trixter747]

Ah, makes much sense. I forget that the bigger the offset, the narrower it is. I'm yet to figure out where those numbers come from...

http://www.discounttiredirect.com/direct/brochure/info/tmpInfoWheelOffsets.jsp

That link should help.

 

[MarvohlusMR2]

im looking at some kosei k1s, 16x7 and 16x7.5 are these good rims, i reallly like how they look, but the whole offset thing baffles me.

 

[TomsMR2]

kosei k1's are excellent rims and they fit perfectly, including the offset... i think they look great too

 

[Andoman66]

my oem's were terrible drivability wise, I spun the car with those easily, now I have 16x7.5 with a 40 mm offset, with some 205/40/16 front and 225/40/16 rear, the car handles great, but I have the trubo cross bar over the engine, it helps a lot. My quarter ile times didn;t change much, because the rim/ tires are a bit smaller than my huge oem tire/wheels (small rim big sidewall)