216 F.3d 582 (7th Cir. 2000)
UNITED STATES OF AMERICA, Plaintiff-Appellee,v.DONALD V. CASHMAN, and  SCOTT D. FEDDERLY, Defendants-Appellants.
Nos. 98-1955, 98-2584
In the  United States Court of Appeals  For the Seventh Circuit
Argued September 14, 1999
Decided June 9, 2000

Appeals from the United States District Court  for the Western District of Wisconsin.  No. 97 CR 102--John C. Shabaz, Chief Judge. [Copyrighted Material Omitted]
Before BAUER, ROVNER, and EVANS, Circuit Judges.
ROVNER, Circuit Judge.


1
Donald Cashman and Scott  Fedderly pleaded guilty to conspiring to  distribute methamphetamine, in violation of 21  U.S.C. sec. 846. Cashman contests the legality of  a traffic stop that culminated in the search of  his automobile and the discovery of evidence  pointing to his involvement in the conspiracy.  Fedderly contests the district court's finding  that he possessed a firearm in the course of the  conspiracy, see U.S.S.G. sec. 2D1.1(b)(1),  asserting, inter alia, that the district court  improperly relied on information which, according  to the terms of his plea agreement, could not be  used against him. We affirm.

I.

2
On August 17, 1997, Cashman was driving his  Chevy Blazer on Interstate Highway 94 through St.  Croix County, Wisconsin, when Wisconsin State  Trooper Jason Spetz pulled him over. Trooper  Spetz effectuated the stop when he noticed a  crack in the windshield of Cashman's Blazer. In  the course of issuing a warning ticket to  Cashman, Spetz asked for and received Cashman's  permission to search the interior of the Blazer.  Inside, the trooper discovered, among other  things, methamphetamine and a spiral index-card  notebook containing drug-related entries.


3
After he was indicted, Cashman moved  unsuccessfully to suppress the evidence that  Trooper Spetz seized from his vehicle. Cashman  argued that the traffic stop that led to the  search was unlawful. However, acting on the  recommendation of the magistrate judge, the  district court concluded that the stop was  justified by the crack in the Blazer's  windshield. Wisconsin law requires that a  vehicle's windshield not be "excessively cracked  or damaged." See Wis. Admin. Code sec. Trans.  305.34(3) (1997). A photograph of the Blazer's  windshield indicated that the crack was from  seven to ten inches long, extending two inches  above the left windshield wiper of the car in its  resting position. Gov. Exs. 1, 1-A; see R. 52 at  2-3; R. 56 at 2. In the court's view, this  appeared to be an "excessive" crack, supplying  Spetz with probable cause to stop Cashman's  vehicle. R. 52 at 2-3; R. 56 at 2. The motion to  suppress was therefore denied, and Cashman  pleaded guilty a short while later.


4
An anonymous tip led the authorities to  Fedderly, a distributor of methamphetamine whom  Cashman supplied. The tipster apprised the Dunn  County, Wisconsin Sheriff's Department by  telephone on August 12, 1997, that Fedderly, who  was wanted on several outstanding warrants, was  staying in a stolen motor home parked in rural  Menominee. After looking the home over and  confirming that it had been reported stolen,  officers performed an inventory search. Inside a  cupboard at the foot of a bed, they discovered a  loaded .22 caliber revolver along with some of  Fedderly's clothing. Elsewhere in the home they  found a baggie containing what appeared to be  marijuana, drug paraphernalia, a wallet with a  social security card issued to Fedderly, and just  under $500 in cash. Fedderly was arrested the  following day. When asked about the gun, he  admitted that it belonged to him and (unlike the  motor home) was not stolen. R. 112 at 12, 21-22;  see also R. 100 para. 14. On August 14, the home  was searched again. That search produced, among  other things, a black nylon tote bag, a digital  scale, syringes, and baggies, as well as a gram  scale and a Tupperware container, both of which  had methamphetamine residue on them.


5
Ultimately, Fedderly pleaded guilty to  conspiring along with Cashman to distribute  methamphetamine. His plea agreement contained a  provision committing him to "make a full,  complete and truthful statement regarding his  involvement in violations of federal criminal  statutes, as well as the involvement of all other  individuals known to the defendant." R. 84 sec.  2. That same provision, however, specified that  "the information provided by the defendant under  the terms of this plea agreement will not be used  against him to determine the applicable  sentencing guideline range except as otherwise  indicated in U.S.S.G. sec.1B1.8(b)." Id.; see  also R. 111 at 8-9.


6
When the probation officer interviewed him prior  to sentencing, Fedderly told the officer that  Cashman had given him the motor home in which the  gun was found because Fedderly had no place to  live. According to Fedderly, Cashman said that  his friends had stolen the motor home and that  the handgun was in the home "at the time."1  Fedderly said that he had never even taken the  gun from the home, let alone used or carried it.  The probation officer included this information  in the pre-sentence report. R. 100 para.para. 40,  50.


7
The Sentencing Guidelines call for a two-level  increase in the defendant's base offense level  when the defendant possessed a dangerous weapon  in the course of a drug-related offense, so long  as it is not "clearly improbable" that the gun  was connected to the offense. U.S.S.G. sec.  2D1.1(b)(1) & comment. (n.3). The probation  officer applied that enhancement in calculating  Fedderly's offense level. R. 100 para. 50.  Although "[t]here is no evidence to suggest  Fedderly used or carried the gun during any drug  transaction," the officer reasoned, "since the  weapon was provided to him by his drug supplier  and was found with other indicia of drug  distribution, we cannot say it is clearly  improbable that the weapon was connected with the  offense." Id. Fedderly contested the propriety of  the enhancement, R. 112 at 18-20, but he did not  argue that consideration of his statement to the  probation officer as to the source of the gun  violated his plea agreement with the government.


8
At sentencing, the district court concluded that  the two-level enhancement for possession of the  gun in the course of the methamphetamine  conspiracy was appropriate. As the court's  remarks reveal, the fact that Cashman had given  Fedderly the gun figured prominently in the  court's rationale.


9
The Court further finds that the loaded .22  caliber handgun was found in the stolen motor  home in which the defendant was sometimes  residing. Initially defendant informed Cragin  [one of the officers who arrested him] the gun  was his and not stolen; has since informed [the]  probation officer that gun was in the motor home  when the vehicle was provided to him by Donald  Cashman. The Court notes that there is no  evidence to suggest that Fedderly used or carried  the gun during any drug transaction. However,  this weapon was provided to him by his drug  supplier and was found with other indicia of drug  distribution.


10
The Court notes that the adjustment should be  applied if the weapon was present. Now the weapon  was present in a mobile home . . . which the  defendant sometimes used. It was in the vicinity,  the immediate vicinity of methamphetamine residue  and drug paraphernalia. That is[,] items which  were normally assimilated with and/or relating to  the distribution of methamphetamine. The Court  cannot find that it is clearly improbable that  the weapon was connected with the offense.


11
Those are the elements. That is the  determination. The Court believes that there is  a reason for this enhancement that has been  suggested in numerous other cases and notes  relating to the enhancement for weapon  possession. It does, as indicated, reflect the  increased danger of violence when drug  traffickers possess weapons. We have a drug  trafficker. We have . . . Donald Cashman, a drug  trafficker, who provided him, [Fedderly] now  tells us in his latest version, the gun. It  certainly wasn't given to him to hunt squirrel.  It certainly wasn't given him as a plaything.


12
He is in a dangerous livelihood. Perhaps [he]  doesn't as yet realize how dangerous it was, but  the fact is this was provided to him by a drug  supplier, it was found with the other evidence  and indicia of drug distribution, and the Court  believes that the weapon was connected with this  offense having previously advised that it cannot  say it is clearly improbable the weapon was  connected. It is in words of the vernacular to  protect the stash and to protect the distribution  thereof and to protect the cash surrounding it  and to protect the defendant when he was in the  mobile home in those surroundings.


13
R. 112 at 22-23. (emphasis ours). Again, Fedderly  raised no objection as to the propriety of taking  into consideration Fedderly's statement to the  probation officer about the source of the gun.


14
The district court sentenced Cashman to a  prison term of 180 months and Fedderly to a term  of 144 months. Cashman now appeals his  conviction, contending that the district court  should have suppressed the evidence seized from  his Blazer. Fedderly challenges his sentence,  arguing that the government failed to establish  that he possessed the revolver discovered in the  mobile home during the conspiracy to distribute  the methamphetamine, that it is clearly  improbable that the gun had any connection to the  conspiracy, and that the district court erred in  considering his statement that Cashman had given  him that gun.

II.
A.

15
Cashman contends that the district court erred  in concluding that Trooper Spetz had probable  cause to effectuate the traffic stop that  culminated in the search of his Blazer. We of  course review the court's probable cause  determination de novo, deferring to any  subsidiary findings of historical fact that are  not clearly erroneous. Ornelas v. United States,  517 U.S. 690, 699, 116 S. Ct. 1657, 1663 (1996);  United States v. Richardson, 208 F.3d 626, 629  (7th Cir. 2000). The particular legal rule  pertinent to this case is straightforward: so  long as the circumstances confronting a police  officer support the reasonable belief that a  driver has committed even a minor traffic  offense, the officer has probable cause to stop  the driver. Whren v. United States, 517 U.S. 806,  116 S. Ct. 1769 (1996).


16
The "Standards for Vehicle Equipment" set forth  in the Wisconsin Administrative Code specify that  the windshield of an automobile "may not be  excessively cracked or damaged." Wis. Admin. Code  sec. Trans. 305.34(3). Excessive cracking or  damage is defined, inter alia, as "a crack  inside, or which extends inside, the windshield  critical area" or "cracks which extend into any  area more than 8 inches from the frame." Id. sec.  Trans. 305.34(3)(a) and (b). The "windshield  critical area" is in turn defined as "that  portion of a motor vehicle windshield normally  used by the driver for necessary observations to  the front of the vehicle[,] . . . includ[ing] the  areas normally swept by a factory installed  windshield wiper system." Id. sec. Trans.  305.05(43).


17
The windshield of Cashman's Blazer in fact was  cracked, and the parties stipulated that Trooper  Spetz "saw a cracked windshield." R. 57 at 7; see  also id. at 25. But Cashman argues that the crack  was not "excessive" as the Wisconsin  Administrative Code defines that term--in other  words, the crack neither extended more than eight  inches away from the frame of the windshield nor  extended into the area of the windshield swept by  the vehicle's windshield wipers.


18
The focus of Cashman's argument is, however,  misplaced. For purposes of the probable cause  analysis, we are not concerned with the precise  length or position of the crack. The propriety of  the traffic stop does not depend, in other words,  on whether Cashman was actually guilty of  committing a traffic offense by driving a vehicle  with an excessively cracked windshield. The  pertinent question instead is whether it was  reasonable for Trooper Spetz to believe that the  windshield was cracked to an impermissible  degree. United States v. Smith, 80 F.3d 215, 219  (7th Cir. 1996).


19
The photographs in the record make plain that  the crack in the Blazer's windshield was  substantial. Gov. Exs. 1, 1-A. As the magistrate  judge noted, and as Cashman concedes, the crack  was between seven and ten inches long, and  extended above the bottom of one of the resting  windshield wipers. R. 52 at 2-3. A trooper in  Spetz's position, then, passing or approaching  Cashman's vehicle on the roadway, could readily  and reasonably think that the crack met the  administrative criteria for excessive cracking  and that Cashman was violating the law by  operating the Blazer in that condition. See  Smith, 80 F.3d at 219. Careful measurement after  the fact might reveal that the crack stopped just  shy of the threshold for "excessive" cracking or  damage; but the Fourth Amendment requires only a  reasonable assessment of the facts, not a  perfectly accurate one. See id. Given the evident  length of the crack and its proximity to the  portion of the windshield swept by the wipers,  Trooper Spetz had probable cause to stop  Cashman's vehicle.

B.

20
Guidelines section 2D1.1(b)(1) directs the court  to increase the defendant's offense level by two  levels if the defendant possessed a dangerous  weapon while committing the offense, unless it is  "clearly improbable" that the weapon had anything  to do with the crime. See id. & comment. (n.3).  As Judge Shabaz recognized, the enhancement  accounts for the heightened risk of violence that  is present when drug traffickers arm themselves.  Id.; see, e.g., United States v. Cain, 155 F.3d  840, 843 (7th Cir. 1998); United States v. Burns,  128 F.3d 553, 555 (7th Cir. 1997). Individuals  who do no more than conspire to distribute  narcotics are nonetheless eligible for the  enhancement, so long as they possess a firearm in  the course of the conspiracy. See United States  v. McClinton, 135 F.3d 1178, 1993 (7th Cir.),  cert. denied, 524 U.S. 921, 118 S. Ct. 2308, and  cert. denied, 525 U.S. 885, 119 S. Ct. 197  (1998); United States v. Wetwattana, 94 F.3d 280,  284 (7th Cir. 1996).


21
For three reasons, Fedderly argues, the district  court erred in enhancing his offense level  pursuant to section 2D1.1(b)(1). First, the  government failed to prove by a preponderance of  the evidence that he possessed the revolver  discovered in the mobile home during the course  of the methamphetamine conspiracy; and thus the  court erred in finding that he did. Second, even  if he did possess the gun, it is, contrary to the  district court's finding, clearly improbable that  the gun was connected to the conspiracy. Finally,  because the plea agreement prohibited the use of  his statement about the source of the gun in  calculating his sentencing range, the district  court was precluded from considering that  statement in assessing the propriety of the  enhancement for possession of the weapon. That  Fedderly possessed the firearm in the course of  the conspiracy and that it was not clearly  improbable the two were connected are findings of  fact that we review for clear error. See United  States v. Berkey, 161 F.3d 1099, 1102 (7th Cir.  1998); Burns, 128 F.3d at 556; United States v.  Tyler, 125 F.3d 1119, 1122 (7th Cir. 1997). As we  have noted, Fedderly raised no objection below to  the district court's consideration of his  statement that Cashman gave him the gun. We  therefore review that issue for plain error.


22
The district court did not clearly err in  finding that Fedderly possessed a weapon while he  conspired with Cashman to distribute  methamphetamine. The superseding indictment  alleged that the conspiracy commenced in or about  June of 1997 and extended to on or about  September 22, 1997 (R. 13 at 1)--although on the  record before us we have no reason to believe  that there was any life left in the enterprise  after Cashman and Fedderly were arrested in mid-  August. The stolen motor home in which the  revolver was located had been parked in Menominee  for several days in August before the local  authorities were alerted to its presence. Until  that time, Fedderly had been in possession and  control of the motor home, although the evidence  suggests that he was not necessarily staying  there. The loaded revolver was found within a  cupboard inside the home. Given the relatively  tight confines of a motor home, one could  reasonably infer that Fedderly had possessed the  weapon inside of it. Indeed, Fedderly admitted at  the time of his arrest that the weapon was his.  These circumstances lend adequate support to the  district court's finding that Fedderly possessed  the weapon during the course of the conspiracy.


23
We likewise find no error in the court's  determination that it was not clearly improbable  that the revolver was connected with the  conspiracy. When the sheriff's deputies searched  the home, they found, in addition to the loaded  revolver, a variety of drug paraphernalia as well  as the gram scale and Tupperware container, both  of which had methamphetamine residue on them.  They also found a black nylon tote bag. According  to the pre-sentence report, the pertinent  findings of which were not contested, four  witnesses had seen Fedderly store methamphetamine  in Tupperware containers, and one witness had  seen him carry these containers in a black nylon  tote bag. R. 100 para.para. 30-32, 34. The record  does not tell us how close these other items may  have been to the cupboard in which the gun was  found. But given the size of a motor home, they  could not have been distant. In any case,  Fedderly bore the burden of proving that it was  clearly unlikely the gun was connected to his  narcotics activity. United States v. Grimm, 170  F.3d 760, 767 (7th Cir. 1999). Although there is  no proof that Fedderly transacted his illicit  business in the motor home or that he carried the  gun with him while transacting that business, for  example, neither is there evidence suggesting  that the presence of both the gun and the drug-  related items within the motor home was  coincidental. See Berkey, 161 F.3d at 1103; see  generally Grimm, 170 F.3d at 767-68.


24
Finally, although it is undisputed that the  plea agreement prohibited the district court from  considering Fedderly's statement as to the source  of the gun, the district court's consideration of  that statement does not rise to the level of  plain error. In order to establish plain error,  a party must not only show that the district  court erred, but that the error, left  uncorrected, would result in a miscarriage of  justice. E.g., United States v. Humphrey, 154  F.3d 668, 670 (7th Cir. 1998); United States v.  Wallace, 32 F.3d 1171, 1174 (7th Cir. 1994). In  the context of sentencing, that means that the  defendant's sentence would have been different  but for the error. United States v. Bauer, 129  F.3d 962, 964 (7th Cir. 1997); United States v.  Hicks, 129 F.3d 376, 378 (7th Cir. 1997). There  is no question here that the district court  relied significantly on Fedderly's protected  statement--the court cited that statement no less  than three times as it overruled Fedderly's  objection to the enhancement. Yet, even when  Fedderly's statement is excluded from the  analysis, there is ample evidence which  establishes that he possessed the gun during the  conspiracy and which affirmatively links the gun  to his narcotics activity. This evidence we have  already noted: the gun was found in the stolen  mobile home that Fedderly possessed for several  days prior to his arrest; Fedderly acknowledged  to arresting officers that the gun belonged to  him (R. 112 at 9); and present along with the gun  in the mobile home were drug paraphernalia, a  scale bearing methamphetamine reside, a container  of the kind in which witnesses had seen Fedderly  store methamphetamine and which, like the scale,  contained methamphetamine residue, as well as a  black nylon tote bag similar to the type one  witness had seen him use to transport the  containers. Given these independent indicia that  Fedderly possessed the gun during and in  connection with the drug conspiracy, we believe  that the court still would have enhanced  Fedderly's base offense level pursuant to section  2D1.1(b)(1) had it not considered Fedderly's  revelation that his drug supplier gave him the  gun. Consequently, we are not convinced that the  court's error in considering that statement was  plain in the sense that it resulted in a more  onerous sentence for Fedderly.

III.

25
Finding no error in the denial of Cashman's  motion to suppress or in the calculation of  Fedderly's sentencing range, we AFFIRM Cashman's  conviction and Fedderly's sentence.



Notes:


1
 To the extent Cashman's statement to Fedderly  suggests that the gun was present in the home at  the time it was stolen, we note that the owners  of the motor home informed the authorities that  they had never owned a firearm. See R. 112 at 11.


